Question

Jeremy saves quarters and dimes. One night he counts his coins and finds that there are 30 coins with a total value of $4.50. How many of each kind of coin does he have? Write your answer as an ordered pair [e.g., if the length and width were 1 and 2 inches respectively, your answer would be (1,2) ]. NEED HELP ASAP

Answer 1

20 dimes and 10 quarters.

Explanation:

Let Q and D stand for the numbers of Quarters and Dimes. I'll use pennies in the calculation just to make it easier (without the decimal point clutter).

We are told that:

Q + D = 30

Rearrange to isolate one of the variables. I'll pick Q:

Q = 30-D

We also know:

25Q + 10D = 450

Substitute the value we found for Q

25(30-D) + 10D = 450

750 - 25D + 10D = 450

-15D = -300

D = 20

Q = 30-D

Q = 10

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Check:

20*(10) + (10*(25) = 450?

200 + 250 = 450 YES