The ratio of the number of blue cards to green cards is 8 : 5. After Seth gives away 40 blue cards and buys another 50 green cards, there is equal number of blue cards and green cards. How many cards does Seth have now?
| |
Blue |
Green |
| Before |
8 u |
5 u |
| Change |
- 40 |
+ 50 |
| After |
8 u - 40 |
5 u + 50 |
The number of blue cards and green cards in the end is the same.
8 u - 40 = 5 u + 50
8 u - 5 u = 50 + 40
3 u = 90
1 u = 90 ÷ 3 = 30
Number of cards that Seth has now
= 8 u - 40 + 5 u + 50
= 8 u + 5 u - 40 + 50
= 13 u + 10
= 13 x 30 + 10
= 390 + 10
= 400
Answer(s): 400
