PSLE John had a total of 93 long and short erasers. After selling an equal number of both types, he had
14 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 -
14 =
34 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 3 and 4 = 12
34 Long erasers =
45 Short erasers
3x44x4 Long erasers =
4x35x3 Short erasers
1216 Long erasers =
1215 Short erasers
|
Long |
Short |
Total |
Before |
16 u |
15 u |
31 u |
Change |
- 12 u |
- 12 u |
- 24 u |
After |
4 u |
3 u |
7 u |
Total number of erasers at first
= 16 u + 15 u
= 31 u
31 u = 93
1 u = 93 ÷ 31 = 3
Total number of erasers left
= 4 u + 3 u
= 7 u
= 7 x 3
= 21
Answer(s): 21