Question

David has $2.25 consisting of 15 coins, all dimes and quarters, in his pocket. How many dimes and quarters does he have?

Answer 1

10 dimes and 5 quarters I believe

Answer 2

Let D=Dimes
Let Q=Quarters

D+Q=15
0.10D+0.25Q=2.25 Multiply the first equation by 0.25 to eliminate Q

0.25D+0.25Q=3.75
0.10D+0.25Q=2.25 Subtract this equation from the first one

0.15D=1.5
D=10 dimes

D+Q=15
Q=15-10=5 Quarters

Therefore, there are 10 dimes and 5 quarters