Joelle had a collection of 1880 grey, silver and gold balls. After Joelle gave away 330 grey balls, the number of grey balls was 120 fewer than the number of silver balls. Given that the number of gold balls was thrice as many as the number of silver balls, how many grey balls did Joelle have at first?
| |
Grey balls |
Silver balls |
Gold balls |
Total |
| Before |
1 u + 330 |
1 u + 120 |
3 u + 360 |
1880 |
| Change |
- 330 |
|
|
|
| After |
1 u |
1 u + 120 |
3 u + 360 |
|
Number of gold balls in the end
= 3 x (1 u + 120)
= 3 u + 360
Total number of balls at first
= 1 u + 330 + 1 u + 120 + 3 u + 360
= 5 u + 810
5 u + 810 = 1880
5 u = 1880 - 810
5 u = 1070
1 u = 1070 ÷ 5 = 214
Number of grey balls that Joelle had at first
= 1 u + 330
= 214 + 330
= 544
Answer(s): 544
