PSLE David had a total of 130 long and short erasers. After selling an equal number of both types, he had
45 of the long erasers and
13 of the short ones left. What was the total number of erasers sold?
Fraction of the long erasers sold
= 1 -
45 =
15 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 1 and 2 = 2
15 Long erasers =
23 Short erasers
1x25x2 Long erasers =
2x13x1 Short erasers
210 Long erasers =
23 Short erasers
|
Long |
Short |
Total |
Before |
10 u |
3 u |
13 u |
Change |
- 2 u |
- 2 u |
- 4 u |
After |
8 u |
1 u |
9 u |
Total number of erasers at first
= 10 u + 3 u
= 13 u
13 u = 130
1 u = 130 ÷ 13 = 10
Total number of erasers sold
= 2 u + 2 u
= 4 u
= 4 x 10
= 40
Answer(s): 40