Answer
$h\geq18$
Work Step by Step
Let h be the number of hours worked.
$7.25h\geq125\longrightarrow$ divide each side by 7.25
$7.25h\div7.25\geq125\div7.25\longrightarrow$ divide
$h\geq17.2$
If the hours are rounded down, the total earned will be less than \$125, so at least 18 hours must be worked.
