The ratio of the number of red stickers to green stickers is 7 : 2. After Tom gives away 10 red stickers and buys another 80 green stickers, there is equal number of red stickers and green stickers. How many stickers does Tom have now?
| |
Red |
Green |
| Before |
7 u |
2 u |
| Change |
- 10 |
+ 80 |
| After |
7 u - 10 |
2 u + 80 |
The number of red stickers and green stickers in the end is the same.
7 u - 10 = 2 u + 80
7 u - 2 u = 80 + 10
5 u = 90
1 u = 90 ÷ 5 = 18
Number of stickers that Tom has now
= 7 u - 10 + 2 u + 80
= 7 u + 2 u - 10 + 80
= 9 u + 70
= 9 x 18 + 70
= 162 + 70
= 232
Answer(s): 232
