Michael had 4 times as many silver notebooks as red notebooks. After giving away 5 silver notebooks and buying another 7 red notebooks, he had an equal number of silver and red notebooks. How many silver notebooks did Michael have at first?
| |
Silver notebooks |
Red notebooks |
| Before |
4 u |
1 u |
| Change |
- 5 |
+ 7 |
| After |
4 u - 5 |
1 u + 7 |
The number of silver and red notebooks is the same in the end.
4 u - 5 = 1 u + 7
4 u - 1 u = 7 + 5
3 u = 5 + 7
3 u = 12
1 u = 12 ÷ 3 = 4
Number of silver notebooks that Michael had at first
= 4 u
= 4 x 4
= 16
Answer(s): 16
