The ratio of the number of red stamps to green stamps is 7 : 3. After Jenson gives away 30 red stamps and buys another 90 green stamps, there is equal number of red stamps and green stamps. How many stamps does Jenson have now?
|
Red |
Green |
Before |
7 u |
3 u |
Change |
- 30 |
+ 90 |
After |
7 u - 30 |
3 u + 90 |
The number of red stamps and green stamps in the end is the same.
7 u - 30 = 3 u + 90
7 u - 3 u = 90 + 30
4 u = 120
1 u = 120 ÷ 4 = 30
Number of stamps that Jenson has now
= 7 u - 30 + 3 u + 90
= 7 u + 3 u - 30 + 90
= 10 u + 60
= 10 x 30 + 60
= 300 + 60
= 360
Answer(s): 360