PSLE The ratio of the number of sweaters to that of shirts in a shop was 7 : 2 at first. After 77 shirts were sold, the ratio of the number of sweaters to that of shirts became 9 : 1. What was the total number of sweaters and shirts in the shop at first?
|
Sweaters |
Shirts |
Total |
Before |
7x9 = 63 u |
2x9 = 18 u |
81 u |
Change |
|
- 77 |
|
After |
9x7 = 63 u |
1x7 = 7 u |
70 u |
The number of sweaters remains unchanged.
Make the number of sweaters the same.
LCM of 2 and 7 is 63.
Number of shirts sold
= 18 u - 7 u
= 11 u
1 u = 77 ÷ 11 = 7
Total number of sweaters and shirts at first
= 63 u + 18 u
= 81 u
= 81 x 7
= 567
Answer(s): 567