There were 10 more 5-cent coins than 20-cent coins in a wallet. Given that the value of all the 20-cent coins were $6.55 more than the value of all the 5-cent coins, how many 5-cent coins were there in the wallet?
| |
20-cent |
5-cent |
Difference |
| Number |
1 u |
1 u + 10 |
|
| Value |
0.20 |
0.05 |
|
| Total value |
0.2 u |
0.05 u + 0.5 |
0.15 u - 0.5 |
Total value of 20-cent coins
= 1 u x 0.20
= 0.2 u
Total value of 5-cent coins
= 0.05 x (1 u + 10)
= 0.05 u + 0.50
Total value of the 20-cent coins that is more than the total value of the 5-cent coins
= 0.2 u - (0.05 u + 0.5)
= 0.2 u - 0.05 u - 0.5
= 0.15 u - 0.5
0.15 u - 0.5 = 6.55
0.15 u = 6.55 + 0.5
0.15 u = 7.05
1 u = 7.05 ÷ 0.15 = 47
Number of 5-cent coins
= 1 u + 10
= 47 + 10
= 57
Answer(s): 57
