Answer:
if you are doing the swimming lessons then it will have to be 22 hours
and for the cashier you can do at least 19 hours
Explanation:
because if you times £8 by 20 for 20 hours you only get £160
and then for the £10 you get the £200
and here i have tried 21 hours timed for the £8 and i got £160
and for the 22 hours you get £176
so basically dont do the swimming job do the cashier