The ratio of the number of green cards to blue cards is 8 : 5. After Jack gives away 20 green cards and buys another 40 blue cards, there is equal number of green cards and blue cards. How many cards does Jack have now?
| |
Green |
Blue |
| Before |
8 u |
5 u |
| Change |
- 20 |
+ 40 |
| After |
8 u - 20 |
5 u + 40 |
The number of green cards and blue cards in the end is the same.
8 u - 20 = 5 u + 40
8 u - 5 u = 40 + 20
3 u = 60
1 u = 60 ÷ 3 = 20
Number of cards that Jack has now
= 8 u - 20 + 5 u + 40
= 8 u + 5 u - 20 + 40
= 13 u + 20
= 13 x 20 + 20
= 260 + 20
= 280
Answer(s): 280
