PSLE Ian had a total of 629 long and short erasers. After selling an equal number of both types, he had
35 of the long erasers and
16 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 -
16 =
56 The number of long erasers and short erasers sold is the same.
Make the numerators the same.
LCM of 2 and 5 = 10
25 Long erasers =
56 Short erasers
2x55x5 Long erasers =
5x26x2 Short erasers
1025 Long erasers =
1012 Short erasers
|
Long |
Short |
Total |
Before |
25 u |
12 u |
37 u |
Change |
- 10 u |
- 10 u |
- 20 u |
After |
15 u |
2 u |
17 u |
Total number of erasers at first
= 25 u + 12 u
= 37 u
37 u = 629
1 u = 629 ÷ 37 = 17
Total number of erasers left
= 15 u + 2 u
= 17 u
= 17 x 17
= 289
Answer(s): 289