PSLE The ratio of the number of skirts to that of vests in a shop was 4 : 3 at first. After 21 vests were sold, the ratio of the number of skirts to that of vests became 5 : 2. What was the total number of skirts and vests in the shop at first?
|
Skirts |
Vests |
Total |
Before |
4x5 = 20 u |
3x5 = 15 u |
35 u |
Change |
|
- 21 |
|
After |
5x4 = 20 u |
2x4 = 8 u |
28 u |
The number of skirts remains unchanged. Make the number of skirts the same.
LCM of 5 and 4 is 20.
Number of vests sold
= 15 u - 8 u
= 7 u
1 u = 21 ÷ 7 = 3
Total number of skirts and vests at first
= 20 u + 15 u
= 35 u
= 35 x 3
= 105
Answer(s): 105