PSLE Charlie had a total of 516 red and blue pens. After selling an equal number of both types, he had
25 of the red pens and
16 of the blue ones left. What was the total number of pens left?
Fraction of the red pens sold
= 1 -
25 =
35 Fraction of the blue pens sold
= 1 -
16 =
56 The number of red pens and blue pens sold is the same.
Make the numerators the same.
LCM of 3 and 5 = 15
35 Long pens =
56 Short pens
3x55x5 Long pens =
5x36x3 Short pens
1525 Long pens =
1518 Short pens
|
Long |
Short |
Total |
Before |
25 u |
18 u |
43 u |
Change |
- 15 u |
- 15 u |
- 30 u |
After |
10 u |
3 u |
13 u |
Total number of pens at first
= 25 u + 18 u
= 43 u
43 u = 516
1 u = 516 ÷ 43 = 12
Total number of pens left
= 10 u + 3 u
= 13 u
= 13 x 12
= 156
Answer(s): 156