RJ’s Plumbing and Heating charges $55 plus $40 per hour for emergency service. Gary remembers being billed over $100 for an emergency call. How long was RJ’s there?

Let x be the number of hours RJ’s was there. Since the bill is over $100, we can write the inequality:
${\displaystyle 55+40x>100}$
Solve for x. Subtract 55 from both sides:
${\displaystyle 40x>45}$
Divide both sides by 40:
${\displaystyle x>1.125}$
So, RJ’s was there for more than 1.125 hours.