The ratio of the number of green cards to red cards is 9 : 4. After Oscar gives away 60 green cards and buys another 70 red cards, there is equal number of green cards and red cards. How many cards does Oscar have now?
| |
Green |
Red |
| Before |
9 u |
4 u |
| Change |
- 60 |
+ 70 |
| After |
9 u - 60 |
4 u + 70 |
The number of green cards and red cards in the end is the same.
9 u - 60 = 4 u + 70
9 u - 4 u = 70 + 60
5 u = 130
1 u = 130 ÷ 5 = 26
Number of cards that Oscar has now
= 9 u - 60 + 4 u + 70
= 9 u + 4 u - 60 + 70
= 13 u + 10
= 13 x 26 + 10
= 338 + 10
= 348
Answer(s): 348
