The ratio of the number of blue cards to green cards is 7 : 3. After Glen gives away 40 blue cards and buys another 60 green cards, there is equal number of blue cards and green cards. How many cards does Glen have now?
| |
Blue |
Green |
| Before |
7 u |
3 u |
| Change |
- 40 |
+ 60 |
| After |
7 u - 40 |
3 u + 60 |
The number of blue cards and green cards in the end is the same.
7 u - 40 = 3 u + 60
7 u - 3 u = 60 + 40
4 u = 100
1 u = 100 ÷ 4 = 25
Number of cards that Glen has now
= 7 u - 40 + 3 u + 60
= 7 u + 3 u - 40 + 60
= 10 u + 20
= 10 x 25 + 20
= 250 + 20
= 270
Answer(s): 270
