PSLE Ben had a total of 516 blue and red pens. After selling an equal number of both types, he had
16 of the blue pens and
25 of the red ones left. What was the total number of pens sold?
Fraction of the blue pens sold
= 1 -
16 =
56 Fraction of the red pens sold
= 1 -
25 =
35 The number of blue pens and red pens sold is the same.
Make the numerators the same.
LCM of 5 and 3 = 15
56 Long pens =
35 Short pens
5x36x3 Long pens =
3x55x5 Short pens
1518 Long pens =
1525 Short pens
|
Long |
Short |
Total |
Before |
18 u |
25 u |
43 u |
Change |
- 15 u |
- 15 u |
- 30 u |
After |
3 u |
10 u |
13 u |
Total number of pens at first
= 18 u + 25 u
= 43 u
43 u = 516
1 u = 516 ÷ 43 = 12
Total number of pens sold
= 15 u + 15 u
= 30 u
= 30 x 12
= 360
Answer(s): 360