Ryan has a total of 44 of gold and black markers.
15 of the gold markers and half of the black markers are new. How many of his black markers are new if he has a total of 13 new markers?
|
Gold markers |
Black markers |
Total |
Total |
5 u |
2 p |
44 |
New |
1 u |
1 p |
13 |
Old |
4 u |
1 p |
31 |
Number of old markers
= 44 - 13
= 31
1 u + 1 p = 13 --- (1)
4 u + 1 p = 31 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 31 - 13
4 u - 1 u = 18
3 u = 18
1 u = 18 ÷ 3 = 6
Number of new black markers
= 13 - 1 u
= 13 - 6
= 7
Answer(s): 7