cost=quantity times cost per one
so he wants to buy a belt (1 belt=1 times cost per belt=1 times $22=$22)
he also wants to buy some shirts (some=unknown=x so x times cost per shirt=x times $17=17x)
x=number of shirts
he has 80 dollars
when you buy something, it is a loss so
80-(22+17x)>0 since he has to have more than or equal to zero since he cannot have negative dollars
the inequality is 80-(22+17x)>0