Joelle had 120 pens.
45 of them were blue pens and the rest were grey pens. After she had given away some blue pens, the ratio of the number of blue pens to the number of grey pens became 3 : 4. How many blue pens did she give away?
| |
Blue |
Grey |
Total |
| Before |
4x4 =
16 u |
1x4 =
4 u |
5x4 =
20 u |
| Change |
- 13 u |
|
|
| After |
3 u |
4 u |
7 u |
The number of grey pens remained unchanged.
LCM of 1 and 4 = 4
Total number of pens at first = 20 u
20 u = 120
1 u = 120 ÷ 20 = 6
Number of blue pens that she gave away
= 16 u - 3 u
= 13 u
= 13 x 6
= 78
Answer(s):78
