Valen and Perry had 236 files together. Valen had 20 more files than Perry. Both of them sold some of their files. Perry sold 10% less files than what Valen sold. In the end, Perry had half as many files left as Valen. How many files had Valen left?
| |
Valen
(1) |
Perry
(2) |
Make p the same
(2)x2 = (3) |
Comparing Valen
and Perry at first |
20 more |
|
|
| Before |
128 |
108 |
216 |
| Change |
- 10 u |
- 9 u |
- 18 u |
| After |
2 p |
1 p |
2 p |
Number of files that Perry had at first
= (236 - 20) ÷ 2
= 216 ÷ 2
= 108
Number of files that Valen had at first
= 108 + 20
= 128
Number of files that Perry sold in percent
= 100% - 10%
= 90%
90% =
90100 =
910 Make p the same.
(1) = (3)
128 - 10 u = 216 - 18 u
18 u - 10 u = 216 - 128
8 u = 88
1 u = 88 ÷ 8 = 11
Number of files that Valen had left
= 128 - 10 u
= 128 - 10 x 11
= 128 - 110
= 18
Answer(s): 18
