Ian has a total of 28 of white and black markers.
16 of the white markers and half of the black markers are new. How many of his black markers are new if he has a total of 10 new markers?
| |
White markers |
Black markers |
Total |
| Total |
6 u |
2 p |
28 |
| New |
1 u |
1 p |
10 |
| Old |
5 u |
1 p |
18 |
Number of old markers
= 28 - 10
= 18
1 u + 1 p = 10 --- (1)
5 u + 1 p = 18 --- (2)
(2) - (1)
(5 u + 1 p) - (1 u + 1 p) = 18 - 10
5 u - 1 u = 8
4 u = 8
1 u = 8 ÷ 4 = 2
Number of new black markers
= 10 - 1 u
= 10 - 2
= 8
Answer(s): 8
