Jane had 120 crayons.
45 of them were black crayons and the rest were blue crayons. After she had given away some black crayons, the ratio of the number of black crayons to the number of blue crayons became 7 : 8. How many black crayons did she give away?
| |
Black |
Blue |
Total |
| Before |
4x8 =
32 u |
1x8 =
8 u |
5x8 =
40 u |
| Change |
- 25 u |
|
|
| After |
7 u |
8 u |
15 u |
The number of blue crayons remained unchanged.
LCM of 1 and 8 = 8
Total number of crayons at first = 40 u
40 u = 120
1 u = 120 ÷ 40 = 3
Number of black crayons that she gave away
= 32 u - 7 u
= 25 u
= 25 x 3
= 75
Answer(s):75
