Ahmad has a total of 62 of silver and white files.
14 of the silver files and half of the white files are new. How many of his white files are new if he has a total of 20 new files?
| |
Silver files |
White files |
Total |
| Total |
4 u |
2 p |
62 |
| New |
1 u |
1 p |
20 |
| Old |
3 u |
1 p |
42 |
Number of old files
= 62 - 20
= 42
1 u + 1 p = 20 --- (1)
3 u + 1 p = 42 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 42 - 20
3 u - 1 u = 22
2 u = 22
1 u = 22 ÷ 2 = 11
Number of new white files
= 20 - 1 u
= 20 - 11
= 9
Answer(s): 9
