Eric has a total of 27 of red and gold notebooks.
13 of the red notebooks and half of the gold notebooks are new. How many of his gold notebooks are new if he has a total of 12 new notebooks?
| |
Red notebooks |
Gold notebooks |
Total |
| Total |
3 u |
2 p |
27 |
| New |
1 u |
1 p |
12 |
| Old |
2 u |
1 p |
15 |
Number of old notebooks
= 27 - 12
= 15
1 u + 1 p = 12 --- (1)
2 u + 1 p = 15 --- (2)
(2) - (1)
(2 u + 1 p) - (1 u + 1 p) = 15 - 12
2 u - 1 u = 3
1 u = 3
1 u = 3 ÷ 1 = 3
Number of new gold notebooks
= 12 - 1 u
= 12 - 3
= 9
Answer(s): 9
