Sam had 4 times as many blue markers as grey markers. After giving away 2 blue markers and buying another 7 grey markers, he had an equal number of blue and grey markers. How many blue markers did Sam have at first?
| |
Blue markers |
Grey markers |
| Before |
4 u |
1 u |
| Change |
- 2 |
+ 7 |
| After |
4 u - 2 |
1 u + 7 |
The number of blue and grey markers is the same in the end.
4 u - 2 = 1 u + 7
4 u - 1 u = 7 + 2
3 u = 2 + 7
3 u = 9
1 u = 9 ÷ 3 = 3
Number of blue markers that Sam had at first
= 4 u
= 4 x 3
= 12
Answer(s): 12
