PSLE Fred had a total of 180 long and short erasers. After selling an equal number of both types, he had
25 of the long erasers and
45 of the short ones left. What was the total number of erasers sold?
Fraction of the long erasers sold
= 1 -
25 =
35 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 3 and 1 = 3
35 Long erasers =
15 Short erasers
3x15x1 Long erasers =
1x35x3 Short erasers
35 Long erasers =
315 Short erasers
|
Long |
Short |
Total |
Before |
5 u |
15 u |
20 u |
Change |
- 3 u |
- 3 u |
- 6 u |
After |
2 u |
12 u |
14 u |
Total number of erasers at first
= 5 u + 15 u
= 20 u
20 u = 180
1 u = 180 ÷ 20 = 9
Total number of erasers sold
= 3 u + 3 u
= 6 u
= 6 x 9
= 54
Answer(s): 54