Vaidev has a total of 30 of grey and blue notebooks.
14 of the grey notebooks and half of the blue notebooks are new. How many of his blue notebooks are new if he has a total of 11 new notebooks?
| |
Grey notebooks |
Blue notebooks |
Total |
| Total |
4 u |
2 p |
30 |
| New |
1 u |
1 p |
11 |
| Old |
3 u |
1 p |
19 |
Number of old notebooks
= 30 - 11
= 19
1 u + 1 p = 11 --- (1)
3 u + 1 p = 19 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 19 - 11
3 u - 1 u = 8
2 u = 8
1 u = 8 ÷ 2 = 4
Number of new blue notebooks
= 11 - 1 u
= 11 - 4
= 7
Answer(s): 7
