a) The variables are:
b)
x + y ≥ 12
x*$0.75 + y*$1.25 ≤ $15
a) First we need to define the variables, in this case we have:
b) Now we want to write the system, we know that he must buy at least 12 items, then:
x + y ≥ 12
And he can spend, at most, $15, then:
x*$0.75 + y*$1.25 ≤ $15
These two inequalities conform the system of inequalities:
x + y ≥ 12
x*$0.75 + y*$1.25 ≤ $15
If you want to learn more about inequalities:
https://brainly.com/question/18881247
#SPJ1