Coin Box Z contains 20-cent coins and Coin Box A contains 5-cent coins. There are 10 more coins in Coin Box A than in Coin Box Z. The amount of money in Coin Box Z is 115¢ more than the amount of money in Coin Box A. How many total coins are there?
| |
Coin Box Z |
Coin Box A |
| Number |
1 u |
1 u + 10 |
| Value |
20¢ |
5¢ |
| Total value |
20 u |
5 u + 50 |
Total value of 20¢ coins in Coin Box Z
= 20 x 1 u
= 20 u
Total value of 5¢ coins in Coin Box A
= 5 x (1 u + 10)
= 5 u + 50
The amount in Coin Box Z is 115¢ more than Coin Box A. If another 115¢ is added into Coin Box A, both Coin Box Z and Coin Box A will have the same amounts of money.
20 u = 5 u + 50 + 115
20 u - 5 u = 50 + 115
15 u = 165
1 u = 165 ÷ 15 = 11
Total number of coins
= 1 u + (1 u + 10)
= 2 u + 10
= 2 x 11 + 10
= 22 + 10
= 32
Answer(s): 32
