Question

A class contributed $8.40 in dimes and quarters to the Red Cross. In all, there were 45 coins. How many coins of each kind were there?

Answer 1

x + y = 45

y = 45-x

.25x + .1y = 8.4

0.25x + 0.1 (45-x)  = 8.4

0.25x + 4.5 - 0.1x = 8.4

0.15x + 4.5 = 8.4

0.15x = 3.90

x = 3.90 / 0.15

x= 26

x + y = 45

(26) + y = 45

y = 45-26 = 19