Neave has a total of 30 of red and brown pencils.
13 of the red pencils and half of the brown pencils are new. How many of his brown pencils are new if he has a total of 13 new pencils?
| |
Red pencils |
Brown pencils |
Total |
| Total |
3 u |
2 p |
30 |
| New |
1 u |
1 p |
13 |
| Old |
2 u |
1 p |
17 |
Number of old pencils
= 30 - 13
= 17
1 u + 1 p = 13 --- (1)
2 u + 1 p = 17 --- (2)
(2) - (1)
(2 u + 1 p) - (1 u + 1 p) = 17 - 13
2 u - 1 u = 4
1 u = 4
1 u = 4 ÷ 1 = 4
Number of new brown pencils
= 13 - 1 u
= 13 - 4
= 9
Answer(s): 9
