Elijah has a total of 34 of blue and grey pencils.
15 of the blue pencils and half of the grey pencils are new. How many of his grey pencils are new if he has a total of 14 new pencils?
|
Blue pencils |
Grey pencils |
Total |
Total |
5 u |
2 p |
34 |
New |
1 u |
1 p |
14 |
Old |
4 u |
1 p |
20 |
Number of old pencils
= 34 - 14
= 20
1 u + 1 p = 14 --- (1)
4 u + 1 p = 20 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 20 - 14
4 u - 1 u = 6
3 u = 6
1 u = 6 ÷ 3 = 2
Number of new grey pencils
= 14 - 1 u
= 14 - 2
= 12
Answer(s): 12