Hilda had the same number of black, green and blue cards at first. After giving some black and green cards and 42 blue cards away, Hilda had 231 cards left. There were 4 times as many black cards as green cards left. The number of blue cards left was 39 fewer than the number of black cards left. How many blue cards did she have at first?
| |
Green |
Black |
Blue |
Total |
| Before |
4 u + 3 |
4 u + 3 |
4 u + 3 |
|
| Change |
- 3 u - 3 |
- 3 |
- 42 |
|
| After |
1 u |
4 u |
4 u - 39 |
231 |
Hilda had the same number of black, green and blue cards at first.
Total number of cards in the end
= 1 u + 4 u + 4 u - 39
= 9 u - 39
9 u - 39 = 231
9 u = 231 + 39
9 u = 270
1 u = 270 ÷ 9 = 30
Number of blue cards that Hilda had at first
= 4 u - 39 + 42
= 4 u + 3
= 4 x 30 + 3
= 123
Answer(s): 123
