PSLE Andy had a total of 30 blue and red pens. After selling an equal number of both types, he had
35 of the blue pens and
45 of the red ones left. What was the total number of pens left?
Fraction of the blue pens sold
= 1 -
35 =
25 Fraction of the red pens sold
= 1 -
45 =
15 The number of blue pens and red pens sold is the same.
Make the numerators the same.
LCM of 2 and 1 = 2
25 Long pens =
15 Short pens
2x15x1 Long pens =
1x25x2 Short pens
25 Long pens =
210 Short pens
|
Long |
Short |
Total |
Before |
5 u |
10 u |
15 u |
Change |
- 2 u |
- 2 u |
- 4 u |
After |
3 u |
8 u |
11 u |
Total number of pens at first
= 5 u + 10 u
= 15 u
15 u = 30
1 u = 30 ÷ 15 = 2
Total number of pens left
= 3 u + 8 u
= 11 u
= 11 x 2
= 22
Answer(s): 22