## College Algebra (6th Edition)

from $80$ to $110$ minutes
Use the given information in the problem to create an inequality based on the original equation. Then subtract $20$, divide by $0.40$, and add $60$ on all three sides to solve for $x$. $C=20+0.40(x-60)$ $28\leq C\leq40$ $28\leq20+0.40(x-60)\leq40$ $8\leq0.40(x-60)\leq20$ $20\leq(x-60)\leq50$ $80\leq x\leq110$