Can some one PLEASE help me with this, i have a TEST tomorrow, and i'm gonna count on u?

Question

1 - Solve the following equation for y in terms of x.
10x + 5y = 20
2 - Solve the following equation for x in terms of y.
7x - 2y = 21
3 - Tina mixes pretzels that sell for $2.00 a pound with cereal that sells for $3.00 a pound. She wants to make an 8 pound mixture to sell for $2.50. How many pounds of each sould Tina use?
10 points for BEST ANSWER Thank you.

Answer 1

1)

10x+ 5y = 20
5y = 20 - 10x (subtracted 10x from both sides)
y = (20 - 10x)/5 (dividing both sides by 5)
y = 4 - 2x (answer)

2)

7x - 2y = 21
7x = 2y + 21 (added 2y to both sides)
x = (2y + 21)/7 (dividing both sides by 7)
x = (2/7)y + 3
x = 0.286y + 3 (answer)

3)

Let the pounds of pretzels she uses be x
Let the pounds of cereal she uses be y
The pretzels would sell for (2 times x) and the cereal would sell for (3 times x)
And you know that the her mixture should sell for $2.5 a pound, so, the total mixture should sell for $20 (8 pounds time $2.5 a pound):
20 = 2x + 3y, meaning the total sales of pretzels and cereal equals $20. This is your first equation. Lets call it (1)
You also know that the mixture weighs 8 pounds, meaning the pounds of pretzels she uses (x) plus the pounds of cereal she uses (y) equals 8:
x + y = 8. This is your second equation. Lets call it (2)
You now have 2 equations:

2x + 3y = 20 (1)
x + y = 8 (2)

From (2), y = 8 - x (subtracted y from both sides)
Lets substitute this value of y into (1)

2x + 3(8 - x) = 20
2x + 24 - 3x = 20 (expanded the bracket)
24 - x = 20
24 = 20 + x (added x to both sides)
4 = x (subtracted 20 from both sides)

Now that we have x, we can get y from (2):

y = 8 - x
y = 8 - 4
y = 4

So, she should use 4 pounds of each :)

Answer 2

I will do the first one and try to learn

10x + 5y = 20 subtract both sides with 10x so that y is alone on one side

10x -10x +5y =20 -10x

5y = 20 - 10x divided both sides with 5 so that you get only 1 y

5y / 5 = 20 / 5 - 10x / 5

y = 4 - 2x done.

===== Q 3
Say number of pound of pretze is X
Say number of pounds of ceral is y

So an equation will be
x + y = 8 number of pound of pretzel + cereal are 8 lbs
2 x + 3 y = 2.5 * 8 8 lb at 2.5 per lb
2x + 3y = 20.

You have two equations

x + y =8 and 2 x + 3 y = 20

First solve y in term of x using the method about. And the substitute it back to the second equation.

Good luck










Good luck.

Answer 3

1)
10x + 5y = 20
5y = 20 -10x
y = (20/5) - (10/5)x
y = 4 - 2x

2)
7x - 2y = 21
7x = 21 + 2y
x = (21/7) + (2/7)y
x = 3 + (2/7)y

3)
x = pounds of pretzels
y = pounds of cereal

x + y = 8 pounds
x = 8 - y

2.00x + 3.00y = 2.50(8)
2x + 3y = 20
2(8 - y) + 3y = 20
16 - 2y + 3y = 20
y = 4 pounds cereal
x = 4 pounds pretzels

And ease up on the shining, people usually answer these questions...haha

Answer 4

1. 12y + 24x = 12
Answer:
12y = 12 - 24x
y = (12/12) - (24/12)x
y = 1 - 2x

2. Same concept as above

3. Trick question - not possible with 8 pound final mixture at $2.50. If you just had 8 pounds of the cheapest item, pretzels, it would be $16.00, so you will not get $2.50 out of an 8 pound mixture with these 2 items.

Answer 5

1. solve for y.
1st subtract 10x from both sides: 5y = 20 - 10x
2nd divide by 5 to get y by itself: y = (20 - 10x)/5 = 4 - 2x = y

2. 1st subtract 7x from both sides: -2y = 21 - 7x
2nd divide both sides by -2: y = (7/2)x - 21/2 = 3.5x - 10.5

3. if x = lbs of pretzels, then (8 - x) = lbs of cereal.
2.00x + 3.00(8 - x) = 2.50(8)
2x + 24 - 3x = 20
-x = -4
x = 4
4lbs of each

Answer 6

1-10x + 5y = 20

10x= 20-5y
all divide 5
(10/5)x = 20/5 - 5y/5
2x = 4 -y
x= (4 - y)/2

so you should have y then put y in this function and you can find x

2- 7x - 2y = 21

-2y = 21-7x
y = (21- 7x ) / -2

in this subject you should have x as well.

3- i think 4 pounds of each

Answer 7

1) y = -2x + 4
2) y = 2/7x + 3
3) 4 pounds, each: 4 pounds pretzels, 4 pounds cereal.

Don't cheat. Knowing the answer before figuring out the problem can help you figure it out, though.

Answer 8

Why oh why didn't you take notes in class?

Why didn't you do your homework?

It is a big party to you, the school? Then, perhaps, you should just become a hostess, and join the party!

We could answer these simple three questions, but, that would not get you any success on the test when there is one different term in each question!

I was SO counting on you to be the smart student that everyone has lauded with such praise! What a disappointment it will be when everyone learns the truth!

Answer 9

1) 10x + 5y = 20
-10x -10x
________________
5y = 20 - 10x
y = 4 - 2x

2) 7x - 2y = 21
+2y +2y
_______________
7x = 21 + 2y
x = 3 + 2/7 y

3) 4 eaach???

Answer 10

1) y=4-2x
2) x=3+(2/7)y
3) 4 pounds each