A jar contains "q" quarters and "d" dimes. There are 7 coins in the jar and the total value of the coins is $1.00

Question

Which system of equations can be used to find how many of each type of coin is in the jar.

A. 0.25q + 0.10d = 1.00

q + d =7

B. 0.25q + 0.10d= 7.00

q + d = 1

C. 0.10q + 0.25d = 1.00

q + d = 7

D. 25q + 10d = 1

q + d = 7

Answer 1

A is the only correct answer: d+q=7 .25q+ .10d = 1

2 quarters and 5 dimes = 2(.25) + 5(.10) = $.50+ $.50 = 50 cents plus 50 cents = $1

2+5 =7

.25q + .10d = 1

.10q + .10d =.7 subtract to eliminate one variable

.15q = .3

q =.3/.15 = 2 quarters

d=7-q = 7-2 = 5 dimes