PSLE Pierre had a total of 220 long and short erasers. After selling an equal number of both types, he had
15 of the long erasers and
13 of the short ones left. What was the total number of erasers left?
Fraction of the long erasers sold
= 1 -
15 =
45 Fraction of the short erasers sold
= 1 -
13 =
23 The number of long erasers and short erasers sold is the same.
Make the numerators the same.
LCM of 4 and 2 = 4
45 Long erasers =
23 Short erasers
4x15x1 Long erasers =
2x23x2 Short erasers
45 Long erasers =
46 Short erasers
|
Long |
Short |
Total |
Before |
5 u |
6 u |
11 u |
Change |
- 4 u |
- 4 u |
- 8 u |
After |
1 u |
2 u |
3 u |
Total number of erasers at first
= 5 u + 6 u
= 11 u
11 u = 220
1 u = 220 ÷ 11 = 20
Total number of erasers left
= 1 u + 2 u
= 3 u
= 3 x 20
= 60
Answer(s): 60