Bottle B contains 20-cent coins and Bottle C contains 5-cent coins. There are 21 more coins in Bottle C than in Bottle B. The amount of money in Bottle B is 285¢ more than the amount of money in Bottle C. How many total coins are there?
| |
Bottle B |
Bottle C |
| Number |
1 u |
1 u + 21 |
| Value |
20¢ |
5¢ |
| Total value |
20 u |
5 u + 105 |
Total value of 20¢ coins in Bottle B
= 20 x 1 u
= 20 u
Total value of 5¢ coins in Bottle C
= 5 x (1 u + 21)
= 5 u + 105
The amount in Bottle B is 285¢ more than Bottle C. If another 285¢ is added into Bottle C, both Bottle B and Bottle C will have the same amounts of money.
20 u = 5 u + 105 + 285
20 u - 5 u = 105 + 285
15 u = 390
1 u = 390 ÷ 15 = 26
Total number of coins
= 1 u + (1 u + 21)
= 2 u + 21
= 2 x 26 + 21
= 52 + 21
= 73
Answer(s): 73
