homework help :)?

Question

when jim cleaned out the reflecting pool at the library he found 20 nickles and quarters. the collection of nickles and quarters totaled 2.60. how many quarters did jim find????
please explain your answer
and write it out if possible

Answer 1

Q + N = 20
Q = 20 - N

2.6 = 0.25Q + 0.05N = 0.25(20 - N) + 0.05N = 5 - 0.25N + 0.05N
2.6 = 5 - 0.2 N

N = 12
Q = 8

Answer 2

I'm assuming you are learning about two equations with two unknowns.

For this problem try to find the 2 equations. Fist we are given that the number of quarters and nickles adds up to 20 so we have
Q+N=20

Then we know that the total amount is $2.60 so we have
.25Q+.05N=2.60

If we multiply the seconde equation by 4 we get the result of:
Q+.2N=10.40 or Q=10.40-.2n

Substituting that equation into the first we have:
10.40 - .2N + N = 20 or .8N= 9.60

Dividing both sides by .8 we get N = 12

Once again going back the the original equation and subbing for N we have:

Q + 12 = 20 and thus Q = 8

Then always check your work and we have 8 quarters equals $2 and 12 nickles is 60 cents so our findings of 8 Quarters and 12 Nickels is correct :o)

Answer 3

Well a simple way is to see how many nickels for the whole thing (they are the smaller amount) 20 x 5 = $1.00. So just keep subtracting five cents and adding quarters! .95/.25 (19 nickels and one quarter) .90/.50, .85/.75, .80/1.00, .75/1.25, .70/1.50, .65/1.75 and finally .60/2.00 (so that's 12 nickels x .05 = $.60 and 8 quarters x .25 = $2.00). I did it this way to make it simple to understand but feanor did it the mathematical formula way!!!