The ratio of the number of blue cards to red cards is 7 : 4. After Bryan gives away 40 blue cards and buys another 80 red cards, there is equal number of blue cards and red cards. How many cards does Bryan have now?
| |
Blue |
Red |
| Before |
7 u |
4 u |
| Change |
- 40 |
+ 80 |
| After |
7 u - 40 |
4 u + 80 |
The number of blue cards and red cards in the end is the same.
7 u - 40 = 4 u + 80
7 u - 4 u = 80 + 40
3 u = 120
1 u = 120 ÷ 3 = 40
Number of cards that Bryan has now
= 7 u - 40 + 4 u + 80
= 7 u + 4 u - 40 + 80
= 11 u + 40
= 11 x 40 + 40
= 440 + 40
= 480
Answer(s): 480
