The ratio of the number of green marbles to blue marbles is 9 : 7. After Wesley gives away 80 green marbles and buys another 90 blue marbles, there is equal number of green marbles and blue marbles. How many marbles does Wesley have now?
| |
Green |
Blue |
| Before |
9 u |
7 u |
| Change |
- 80 |
+ 90 |
| After |
9 u - 80 |
7 u + 90 |
The number of green marbles and blue marbles in the end is the same.
9 u - 80 = 7 u + 90
9 u - 7 u = 90 + 80
2 u = 170
1 u = 170 ÷ 2 = 85
Number of marbles that Wesley has now
= 9 u - 80 + 7 u + 90
= 9 u + 7 u - 80 + 90
= 16 u + 10
= 16 x 85 + 10
= 1360 + 10
= 1370
Answer(s): 1370
