The ratio of the number of green coins to red coins is 8 : 5. After Peter gives away 50 green coins and buys another 70 red coins, there is equal number of green coins and red coins. How many coins does Peter have now?
| |
Green |
Red |
| Before |
8 u |
5 u |
| Change |
- 50 |
+ 70 |
| After |
8 u - 50 |
5 u + 70 |
The number of green coins and red coins in the end is the same.
8 u - 50 = 5 u + 70
8 u - 5 u = 70 + 50
3 u = 120
1 u = 120 ÷ 3 = 40
Number of coins that Peter has now
= 8 u - 50 + 5 u + 70
= 8 u + 5 u - 50 + 70
= 13 u + 20
= 13 x 40 + 20
= 520 + 20
= 540
Answer(s): 540
