PSLE Cody had a total of 180 red and blue pens. After selling an equal number of both types, he had
12 of the red pens and
35 of the blue ones left. What was the total number of pens left?
Fraction of the red pens sold
= 1 -
12 =
12 Fraction of the blue pens sold
= 1 -
35 =
25 The number of red pens and blue pens sold is the same.
Make the numerators the same.
LCM of 1 and 2 = 2
12 Long pens =
25 Short pens
1x22x2 Long pens =
2x15x1 Short pens
24 Long pens =
25 Short pens
|
Long |
Short |
Total |
Before |
4 u |
5 u |
9 u |
Change |
- 2 u |
- 2 u |
- 4 u |
After |
2 u |
3 u |
5 u |
Total number of pens at first
= 4 u + 5 u
= 9 u
9 u = 180
1 u = 180 ÷ 9 = 20
Total number of pens left
= 2 u + 3 u
= 5 u
= 5 x 20
= 100
Answer(s): 100