Suppose you just have just enough dimes and quarters to pay for a loaf of bread and quart of milk,?

Question

which cost $3.45. You have a total of 15 dimes and quarters.

Let d = the number of dimes you have.

Let q = the number of quarters you have.

a. Write a system of equations that models the information given above.

b. Solve the system for the number of dimes and quarters you have. You may want to solve this by graphing.

Answer 1

a. 0.10d + 0.25q = 3.45
d + q = 15

b. Since d + q = 15, d = 15 - q. Substitute this in to the first equation to get:
0.10(15-q) + 0.25q = 3.45
1.5 - .1q + .25q = 3.45
1.5 + .15q = 3.45
0.15q = 1.95
q = 13

So you have 13 quarters and 2 dimes.

To check 13 quarters is worth $3.25.
2 dimes is worth $0.20.
This adds up to 15 coins and $3.45.

By the way, to graph, simply change d to x and q to y.

I hope this helps!

Answer 2

d + q = 15

.10d + .25q = 3.45 or 10d + 25 q = 345


solve
subtract 10d + 10q = 150

15q = 195

q = 13
d = 2

Answer 3

Well I never passed algebra or even "got it"
So lets say you've been collecting the state quarters so you have a few more dimes on hand.
To make $3.45 you need 9 quarters thats $2.25 =9q and 12 dimes $1.20 =12d.

$2.25
+ $1.20
--------------
$3.45