Emma had a collection of 2450 grey, yellow and silver balls. After Emma gave away 280 grey balls, the number of grey balls was 130 fewer than the number of yellow balls. Given that the number of silver balls was twice as many as the number of yellow balls, how many grey balls did Emma have at first?
| |
Grey balls |
Yellow balls |
Silver balls |
Total |
| Before |
1 u + 280 |
1 u + 130 |
2 u + 260 |
2450 |
| Change |
- 280 |
|
|
|
| After |
1 u |
1 u + 130 |
2 u + 260 |
|
Number of silver balls in the end
= 2 x (1 u + 130)
= 2 u + 260
Total number of balls at first
= 1 u + 280 + 1 u + 130 + 2 u + 260
= 4 u + 670
4 u + 670 = 2450
4 u = 2450 - 670
4 u = 1780
1 u = 1780 ÷ 4 = 445
Number of grey balls that Emma had at first
= 1 u + 280
= 445 + 280
= 725
Answer(s): 725
