Cathy had 120 pencils.
23 of them were black pencils and the rest were silver pencils. After she had given away some black pencils, the ratio of the number of black pencils to the number of silver pencils became 3 : 4. How many pencils did she have in the end?
| |
Black |
Silver |
Total |
| Before |
2x4 =
8 u |
1x4 =
4 u |
3x4 =
12 u |
| Change |
- 5 u |
|
|
| After |
3 u |
4 u |
7 u |
The number of silver pencils remained unchanged.
LCM of 1 and 4 = 4
Total number of pencils at first = 12 u
12 u = 120
1 u = 120 ÷ 12 = 10
Number of pencils that Cathy had in the end
= 3 u + 4 u
= 7 u
= 7 x 10
= 70
Answer(s):70
