PSLE The ratio of the number of vests to that of coats in a shop was 11 : 10 at first. After 91 coats were sold, the ratio of the number of vests to that of coats became 9 : 7. What was the total number of vests and coats in the shop at first?
|
Vests |
Coats |
Total |
Before |
11x9 = 99 u |
10x9 = 90 u |
189 u |
Change |
|
- 91 |
|
After |
9x11 = 99 u |
7x11 = 77 u |
176 u |
The number of vests remains unchanged.
Make the number of vests the same.
LCM of 10 and 11 is 99.
Number of coats sold
= 90 u - 77 u
= 13 u
1 u = 91 ÷ 13 = 7
Total number of vests and coats at first
= 99 u + 90 u
= 189 u
= 189 x 7
= 1323
Answer(s): 1323