PSLE Will had a total of 52 red and blue pens. After selling an equal number of both types, he had
45 of the red pens and
13 of the blue ones left. What was the total number of pens left?
Fraction of the red pens sold
= 1 -
45 =
15 Fraction of the blue pens sold
= 1 -
13 =
23 The number of red pens and blue pens sold is the same.
Make the numerators the same.
LCM of 1 and 2 = 2
15 Long pens =
23 Short pens
1x25x2 Long pens =
2x13x1 Short pens
210 Long pens =
23 Short pens
|
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 pens at first
= 10 u + 3 u
= 13 u
13 u = 52
1 u = 52 ÷ 13 = 4
Total number of pens left
= 8 u + 1 u
= 9 u
= 9 x 4
= 36
Answer(s): 36