Bottle X contains 10-cent coins and Bottle Y contains 5-cent coins. There are 12 more coins in Bottle Y than in Bottle X. The amount of money in Bottle X is 15¢ more than the amount of money in Bottle Y. How many total coins are there?
| |
Bottle X |
Bottle Y |
| Number |
1 u |
1 u + 12 |
| Value |
10¢ |
5¢ |
| Total value |
10 u |
5 u + 60 |
Total value of 10¢ coins in Bottle X
= 10 x 1 u
= 10 u
Total value of 5¢ coins in Bottle Y
= 5 x (1 u + 12)
= 5 u + 60
The amount in Bottle X is 15¢ more than Bottle Y. If another 15¢ is added into Bottle Y, both Bottle X and Bottle Y will have the same amounts of money.
10 u = 5 u + 60 + 15
10 u - 5 u = 60 + 15
5 u = 75
1 u = 75 ÷ 5 = 15
Total number of coins
= 1 u + (1 u + 12)
= 2 u + 12
= 2 x 15 + 12
= 30 + 12
= 42
Answer(s): 42
