Oliver has a total of 34 of pink and brown notebooks.
14 of the pink notebooks and half of the brown notebooks are new. How many of his brown notebooks are new if he has a total of 13 new notebooks?
| |
Pink notebooks |
Brown notebooks |
Total |
| Total |
4 u |
2 p |
34 |
| New |
1 u |
1 p |
13 |
| Old |
3 u |
1 p |
21 |
Number of old notebooks
= 34 - 13
= 21
1 u + 1 p = 13 --- (1)
3 u + 1 p = 21 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 21 - 13
3 u - 1 u = 8
2 u = 8
1 u = 8 ÷ 2 = 4
Number of new brown notebooks
= 13 - 1 u
= 13 - 4
= 9
Answer(s): 9
