Answer:
8 hours
Step-by-step explanation:
First, let's find how much Bentley gets from clearing tables.
5 hours • $8 per hour = $40 total
We can take $40 off his $180 total, leaving the rest for when we figure out how much he needs to work lifeguarding.
$180 needed - $40 earned = $140 left to earn
We know that Bentley makes $18 an hour lifeguarding, so in order to get the number of hours he would need to work in order to make $140, we can divide it by $18.
$140 needed ÷ $18 per hour = 7.77...
We need to convert this to a whole number because we're talking about hours worked, so Bentley would need to work 8 hours lifeguarding to make $140 more. He can only work 15 hours total, so let's check if this exceeds his limit.
5 hours clearing tables + 8 hours lifeguarding = 13 hours < 15 hours max
It is possible to make $180 total from this work schedule, so your answer would be 8 hours.