Bryan has a total of 58 of brown and black notebooks.
13 of the brown notebooks and half of the black notebooks are new. How many of his black notebooks are new if he has a total of 23 new notebooks?
| |
Brown notebooks |
Black notebooks |
Total |
| Total |
3 u |
2 p |
58 |
| New |
1 u |
1 p |
23 |
| Old |
2 u |
1 p |
35 |
Number of old notebooks
= 58 - 23
= 35
1 u + 1 p = 23 --- (1)
2 u + 1 p = 35 --- (2)
(2) - (1)
(2 u + 1 p) - (1 u + 1 p) = 35 - 23
2 u - 1 u = 12
1 u = 12
1 u = 12 ÷ 1 = 12
Number of new black notebooks
= 23 - 1 u
= 23 - 12
= 11
Answer(s): 11
