Albert and Simon had 72 pens together. Simon had 4 less pens than Albert. Both of them sold some of their pens. Simon sold 25% more pens than what Albert sold. In the end, Simon had half as many pens left as Albert. How many pens had Simon left?
| |
Albert
(1) |
Simon
(2) |
Make p the same
(2)x2 = (3) |
Comparing Albert
and Simon at first |
4 more |
|
|
| Before |
38 |
34 |
68 |
| Change |
- 4 u |
- 5 u |
- 10 u |
| After |
2 p |
1 p |
2 p |
Number of pens that Simon had at first
= (72 - 4) ÷ 2
= 68 ÷ 2
= 34
Number of pens that Albert had at first
= 34 + 4
= 38
Number of pens that Simon sold in percent
= 100% + 25%
= 125%
125% =
125100 =
54 Make p the same.
(1) = (3)
38 - 4 u = 68 - 10 u
10 u - 4 u = 68 - 38
6 u = 30
1 u = 30 ÷ 6 = 5
Number of pens that Simon had left
= 34 - 5 u
= 34 - 5 x 5
= 34 - 25
= 9
Answer(s): 9
