Vincent has a total of 63 of grey and blue notebooks.
15 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 15 new notebooks?
| |
Grey notebooks |
Blue notebooks |
Total |
| Total |
5 u |
2 p |
63 |
| New |
1 u |
1 p |
15 |
| Old |
4 u |
1 p |
48 |
Number of old notebooks
= 63 - 15
= 48
1 u + 1 p = 15 --- (1)
4 u + 1 p = 48 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 48 - 15
4 u - 1 u = 33
3 u = 33
1 u = 33 ÷ 3 = 11
Number of new blue notebooks
= 15 - 1 u
= 15 - 11
= 4
Answer(s): 4
