Abi had a collection of 2120 red, green and black balls. After Abi gave away 210 red balls, the number of red balls was 190 fewer than the number of green balls. Given that the number of black balls was twice as many as the number of green balls, how many red balls did Abi have at first?
| |
Red balls |
Green balls |
Black balls |
Total |
| Before |
1 u + 210 |
1 u + 190 |
2 u + 380 |
2120 |
| Change |
- 210 |
|
|
|
| After |
1 u |
1 u + 190 |
2 u + 380 |
|
Number of black balls in the end
= 2 x (1 u + 190)
= 2 u + 380
Total number of balls at first
= 1 u + 210 + 1 u + 190 + 2 u + 380
= 4 u + 780
4 u + 780 = 2120
4 u = 2120 - 780
4 u = 1340
1 u = 1340 ÷ 4 = 335
Number of red balls that Abi had at first
= 1 u + 210
= 335 + 210
= 545
Answer(s): 545
