To solve for a variable, use inverse operations to undo the operations in the inequality. Be sure to do the same operation to all parts of the inequality.
Solve for f.
5 < f + 13 ≤ 5
5 13 < f + 13 13 ≤ 5 13


Subtract 13 from each part of the inequality

18 < f ≤ 8 

Simplify 