There were 7 more 5-cent coins than 20-cent coins in a bag. Given that the value of all the 20-cent coins were $8.35 more than the value of all the 5-cent coins, how many 5-cent coins were there in the bag?
| |
20-cent |
5-cent |
Difference |
| Number |
1 u |
1 u + 7 |
|
| Value |
0.20 |
0.05 |
|
| Total value |
0.2 u |
0.05 u + 0.35 |
0.15 u - 0.35 |
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 + 7)
= 0.05 u + 0.35
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 + 0.35)
= 0.2 u - 0.05 u - 0.35
= 0.15 u - 0.35
0.15 u - 0.35 = 8.35
0.15 u = 8.35 + 0.35
0.15 u = 8.70
1 u = 8.70 ÷ 0.15 = 58
Number of 5-cent coins
= 1 u + 7
= 58 + 7
= 65
Answer(s): 65
