Shannon had the same number of yellow, grey and red pens at first. After giving some yellow and grey pens and 63 red pens away, Shannon had 210 pens left. There were 3 times as many yellow pens as grey pens left. The number of red pens left was 42 fewer than the number of yellow pens left. How many red pens did she have at first?
| |
Grey |
Yellow |
Red |
Total |
| Before |
3 u + 21 |
3 u + 21 |
3 u + 21 |
|
| Change |
- 2 u - 21 |
- 21 |
- 63 |
|
| After |
1 u |
3 u |
3 u - 42 |
210 |
Shannon had the same number of yellow, grey and red pens at first.
Total number of pens in the end
= 1 u + 3 u + 3 u - 42
= 7 u - 42
7 u - 42 = 210
7 u = 210 + 42
7 u = 252
1 u = 252 ÷ 7 = 36
Number of red pens that Shannon had at first
= 3 u - 42 + 63
= 3 u + 21
= 3 x 36 + 21
= 129
Answer(s): 129
