PSLE Harry had a total of 155 long and short erasers. After selling an equal number of both types, he had
16 of the long erasers and
45 of the short ones left. What was the total number of erasers left?
Fraction of the long erasers sold
= 1 -
16 =
56 Fraction of the short erasers sold
= 1 -
45 =
15 The number of long erasers and short erasers sold is the same.
Make the numerators the same.
LCM of 5 and 1 = 5
56 Long erasers =
15 Short erasers
5x16x1 Long erasers =
1x55x5 Short erasers
56 Long erasers =
525 Short erasers
|
Long |
Short |
Total |
Before |
6 u |
25 u |
31 u |
Change |
- 5 u |
- 5 u |
- 10 u |
After |
1 u |
20 u |
21 u |
Total number of erasers at first
= 6 u + 25 u
= 31 u
31 u = 155
1 u = 155 ÷ 31 = 5
Total number of erasers left
= 1 u + 20 u
= 21 u
= 21 x 5
= 105
Answer(s): 105