Answer:
lifeguarding: 9 hours/clearing tables: 2 hours
Step-by-step explanation:
if you do $18×$9 it will get you to $162 which is the closed number you can get by adding $18 without going over the amount. then you would add $162+$8 for clearing tables which would get you at $170 but the total amount is $178 so then you would just add $8 for 1 more hour which would leave you at $178.