He earns 1020$ he is going to work 70 hours so :- First 40 hours are each for 12$ so they will cost 480$ as a total Then the next 10 hours will cost 6$ so 60$ as a total since he is going to work for 70 hours then there are more 20 hours which will be charged for double(24$) each so 480$ as a total So he earned 480$+60$+480$=1020$ in 70 hours
