Hmmm... let's say kids=x and dogs=y.
33 heads...33 kids and dogs, combined.
x+y=33
Legs=2x+4y
2x+4y=92
Change the first equation to represent one variable.
x+y=33
x=33-y
Insert that (what we have determined x equals) in the second equation, as x
2(33-y)+4y=92
66-2y+4y=92
2y=26
y=13
There are 13 dogs and 20 kids.
2006-08-15 16:14:39
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answer #1
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answered by Master Maverick 6
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There are 20 kids and 13 dogs. This is how you would do it:
Dogs have four legs and kids have two.
x = # of kids
y = # of dogs
92 = 2x + 4y (this is the "legs"equation)
33 = x + y (this is the "heads" equation)
The best way to do this is with substitution.
First you should get x by itself in the second equation.
33 - y = x
Then you substitute 33 -y for x in the other equation.
92 = 2(33-y) +4y
Then you solve for you in that equation.
92 = 2(33-y) +4y
92 = 66 - 2y +4y
92 = 66 + 2y
26 = 2y
y = 13
Then you plug the y value back into one of the equations to find x.
33 = x + y
33 = x + (13)
x = 20
So, there are 20 kids and 13 dogs.
You could also use combination when you have the two equations. It would look like this:
Multiply the second equation by -2 so the x's will cancel when you combine.
92 = 2x + 4y
(33 = x + y) -2
Combine the equations and solve.
92 = 2x + 4y
-66 = -2x + -2y
----------------------
26 = 2y
y = 13
33 = x + y
33 = x + (13)
x = 20
Either way works.
2006-08-15 23:24:25
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answer #2
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answered by TheBestSaul 2
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13 dogs and 20 kids
13 dogs = 13 heads, 52 legs
20 kids = 20 heads, 40 legs
For a total of 33 heads and 92 legs
2006-08-15 23:15:25
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answer #3
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answered by Molly M 3
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This is a two operation problem, since there are two variables.
Kids should be represented by "a" and dogs by "b".
Since there are 33 of them combinded, it would imply that
a + b = 33 (i)
If you then know that for each person there are two legs (hopefully) and for each dog there are 4, it would imply that
2a + 4b = 92
Divide both sides by 2.
a + 2b = 46 (ii)
If you are good enough at math, you would then know that b is equal to 13, but for the purpose of this demonstration, I will work it out:
Subtract both sides of equation (ii) by 2b.
a = -2b + 46
Subtract both sides of equation (i) by b.
a= -b + 33
Subtract equation (ii) by equation (i).
0 = -b + 13
b = 13
a + 13 = 33
a = 20
a = 13, b = 20
Hope I could help!
2006-08-15 23:34:23
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answer #4
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answered by Elerth Morrow ™ 5
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x = number of kids
y = number of dogs
So, for head's number, you have
x + y = 33 (since every kid and every dog have onle one head, the sum of kids and dogs have to match the number of heads)
For legs, every kid has 2 legs, and every dog have 4. So
2x + 4y = 92 (the number of kid's legs and the number of dog's legs have to be 92)
so, you have to solve two simultaneous equations:
x + y = 33
2x + 4y = 92
Solving, you have that there are 20 kids and 13 dogs.
2006-08-15 23:22:32
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answer #5
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answered by Lucas 2
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20 kids & 13 dogs including Patricia G.
2006-08-15 23:16:26
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answer #6
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answered by Shot At Sight 3
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Okay I have been working on it for a little while now and I think I have it down to 20 kids and 13 dogs. It took me a while but I feel good after finally getting it. Thanks for the mental workout. I guess it's been a while and I kind of needed it. Good one.
2006-08-15 23:19:45
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answer #7
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answered by ttti 3
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13 dogs, 20 kids
2006-08-15 23:16:37
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answer #8
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answered by bcb8504 3
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Well, obviously there are 33 total.
20 kids
13 dogs
2006-08-15 23:14:52
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answer #9
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answered by kristnanne19 3
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20 Kids and 13 Dogs
Solution: x=number of kids, y=number of dogs
x+y=13
2x+4y=92
x=(33-y)
2(33-y)+4y=92
66-2y+4y=92
y=13
x=20
2006-08-15 23:18:39
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answer #10
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answered by ermacx27 2
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