Your answers are Equation A (8(4+x) = 72, and Answer C (5 hours).
1) Figure out how much of the total money she earned on Friday. 4*8= 32 2) She has 72 dollars total and 32 dollars were earned on Friday, meaning the rest was earned on Saturday. 72-32= 40 3) She earned 40 dollars on Saturday for 8 dollars an hour, so now you divide 40 by 8 and you get 5. She worked 5 hours on Saturday.