PSLE Jack had a total of 120 long and short erasers. After selling an equal number of both types, he had
35 of the long erasers and
15 of the short ones left. What was the total number of erasers left?
Fraction of the long erasers sold
= 1 -
35 =
25 Fraction of the short erasers sold
= 1 -
15 =
45 The number of long erasers and short erasers sold is the same.
Make the numerators the same.
LCM of 2 and 4 = 4
25 Long erasers =
45 Short erasers
2x25x2 Long erasers =
4x15x1 Short erasers
410 Long erasers =
45 Short erasers
|
Long |
Short |
Total |
Before |
10 u |
5 u |
15 u |
Change |
- 4 u |
- 4 u |
- 8 u |
After |
6 u |
1 u |
7 u |
Total number of erasers at first
= 10 u + 5 u
= 15 u
15 u = 120
1 u = 120 ÷ 15 = 8
Total number of erasers left
= 6 u + 1 u
= 7 u
= 7 x 8
= 56
Answer(s): 56