Question

You have 20 coins in your pocket that are either quarter or dimes. They total $3.95. How many quarters do you have? A.16 B.13 C.12 D.10 E.15

Answer 1

B. 13

Explanation:

Solve this by setting up system of equations:

0.25x + 0.10y = 3.95

x + y = 20

x equals the number of quarters and y equals the number of dimes. 0.25 is the value of a quarter and 0.10 is the value of a dime.

1. Multiply one equation to have the same coefficient as the other

0.10 · (x + y = 20) = 0.10x + 0.10y = 2

2. Subtract to find the value of one variable

0.25x + 0.10y = 3.95

- 0.10x + 0.10y = 2

0.15x = 1.95

3. Solve for x by dividing both sides by 0.15

x = 13