Will has a total of 47 of black and yellow files.
13 of the black files and half of the yellow files are new. How many of his yellow files are new if he has a total of 19 new files?
| |
Black files |
Yellow files |
Total |
| Total |
3 u |
2 p |
47 |
| New |
1 u |
1 p |
19 |
| Old |
2 u |
1 p |
28 |
Number of old files
= 47 - 19
= 28
1 u + 1 p = 19 --- (1)
2 u + 1 p = 28 --- (2)
(2) - (1)
(2 u + 1 p) - (1 u + 1 p) = 28 - 19
2 u - 1 u = 9
1 u = 9
1 u = 9 ÷ 1 = 9
Number of new yellow files
= 19 - 1 u
= 19 - 9
= 10
Answer(s): 10
