Coin Box S contains 50-cent coins and Coin Box T contains 20-cent coins. There are 30 more coins in Coin Box T than in Coin Box S. The amount of money in Coin Box S is 210¢ more than the amount of money in Coin Box T. How many total coins are there?
| |
Coin Box S |
Coin Box T |
| Number |
1 u |
1 u + 30 |
| Value |
50¢ |
20¢ |
| Total value |
50 u |
20 u + 600 |
Total value of 50¢ coins in Coin Box S
= 50 x 1 u
= 50 u
Total value of 20¢ coins in Coin Box T
= 20 x (1 u + 30)
= 20 u + 600
The amount in Coin Box S is 210¢ more than Coin Box T. If another 210¢ is added into Coin Box T, both Coin Box S and Coin Box T will have the same amounts of money.
50 u = 20 u + 600 + 210
50 u - 20 u = 600 + 210
30 u = 810
1 u = 810 ÷ 30 = 27
Total number of coins
= 1 u + (1 u + 30)
= 2 u + 30
= 2 x 27 + 30
= 54 + 30
= 84
Answer(s): 84
