The ratio of the number of red stickers to green stickers is 3 : 1. After Sam gives away 10 red stickers and buys another 70 green stickers, there is equal number of red stickers and green stickers. How many stickers does Sam have now?
| |
Red |
Green |
| Before |
3 u |
1 u |
| Change |
- 10 |
+ 70 |
| After |
3 u - 10 |
1 u + 70 |
The number of red stickers and green stickers in the end is the same.
3 u - 10 = 1 u + 70
3 u - 1 u = 70 + 10
2 u = 80
1 u = 80 ÷ 2 = 40
Number of stickers that Sam has now
= 3 u - 10 + 1 u + 70
= 3 u + 1 u - 10 + 70
= 4 u + 60
= 4 x 40 + 60
= 160 + 60
= 220
Answer(s): 220
