Question

Kitara has 100 quarters and dimes. Their total value is $19. How many of each coin does Kitara have?

Answer 1

Q + d = 100 so q = 100 - d
0.25q + 0.10d = 19

substitute q = 100 - d into 0.25q + 0.10d = 19

0.25q + 0.10d = 19
0.25(100 - d) + 0.10d = 19
25 - 0.25d + 0.10d = 19
-0.15d = -6
        d = 40

q = 100 - 40 = 60

answer
Kitara has 60 quarters and 40 dimes