Daniel and Ivan had 57 notebooks together. Ivan had 7 less notebooks than Daniel. Both of them sold some of their notebooks. Ivan sold 25% more notebooks than what Daniel sold. In the end, Ivan had half as many notebooks left as Daniel. How many notebooks had Ivan left?
| |
Daniel
(1) |
Ivan
(2) |
Make p the same
(2)x2 = (3) |
Comparing Daniel
and Ivan at first |
7 more |
|
|
| Before |
32 |
25 |
50 |
| Change |
- 4 u |
- 5 u |
- 10 u |
| After |
2 p |
1 p |
2 p |
Number of notebooks that Ivan had at first
= (57 - 7) ÷ 2
= 50 ÷ 2
= 25
Number of notebooks that Daniel had at first
= 25 + 7
= 32
Number of notebooks that Ivan sold in percent
= 100% + 25%
= 125%
125% =
125100 =
54 Make p the same.
(1) = (3)
32 - 4 u = 50 - 10 u
10 u - 4 u = 50 - 32
6 u = 18
1 u = 18 ÷ 6 = 3
Number of notebooks that Ivan had left
= 25 - 5 u
= 25 - 5 x 3
= 25 - 15
= 10
Answer(s): 10
