Ahmad has a total of 36 of grey and black markers.
16 of the grey markers and half of the black markers are new. How many of his black markers are new if he has a total of 8 new markers?
| |
Grey markers |
Black markers |
Total |
| Total |
6 u |
2 p |
36 |
| New |
1 u |
1 p |
8 |
| Old |
5 u |
1 p |
28 |
Number of old markers
= 36 - 8
= 28
1 u + 1 p = 8 --- (1)
5 u + 1 p = 28 --- (2)
(2) - (1)
(5 u + 1 p) - (1 u + 1 p) = 28 - 8
5 u - 1 u = 20
4 u = 20
1 u = 20 ÷ 4 = 5
Number of new black markers
= 8 - 1 u
= 8 - 5
= 3
Answer(s): 3
