Ivan has a total of 16 of purple and blue pencils.
13 of the purple pencils and half of the blue pencils are new. How many of his blue pencils are new if he has a total of 7 new pencils?
| |
Purple pencils |
Blue pencils |
Total |
| Total |
3 u |
2 p |
16 |
| New |
1 u |
1 p |
7 |
| Old |
2 u |
1 p |
9 |
Number of old pencils
= 16 - 7
= 9
1 u + 1 p = 7 --- (1)
2 u + 1 p = 9 --- (2)
(2) - (1)
(2 u + 1 p) - (1 u + 1 p) = 9 - 7
2 u - 1 u = 2
1 u = 2
1 u = 2 ÷ 1 = 2
Number of new blue pencils
= 7 - 1 u
= 7 - 2
= 5
Answer(s): 5
