Kathy had a collection of 1620 red, silver and green marbles. After Kathy gave away 230 red marbles, the number of red marbles was 140 fewer than the number of silver marbles. Given that the number of green marbles was four times as many as the number of silver marbles, how many red marbles did Kathy have at first?
| |
Red marbles |
Silver marbles |
Green marbles |
Total |
| Before |
1 u + 230 |
1 u + 140 |
4 u + 560 |
1620 |
| Change |
- 230 |
|
|
|
| After |
1 u |
1 u + 140 |
4 u + 560 |
|
Number of green marbles in the end
= 4 x (1 u + 140)
= 4 u + 560
Total number of marbles at first
= 1 u + 230 + 1 u + 140 + 4 u + 560
= 6 u + 930
6 u + 930 = 1620
6 u = 1620 - 930
6 u = 690
1 u = 690 ÷ 6 = 115
Number of red marbles that Kathy had at first
= 1 u + 230
= 115 + 230
= 345
Answer(s): 345
