For this case, the first thing we must do is define variables.
We have then:
x: number of packs of 4
y: number of notebooks
The equation modeling the problem is given by:
[tex] y = 4x
[/tex]
Three packs of notebooks are sold.
Therefore, for x = 3 we have:
[tex] y = 4 (3)
y = 12
[/tex]
As the number of notebooks are 28, then the remaining amount is:
[tex] 28-12 = 16
[/tex]
Answer:
There are 16 notebooks left
