You evidence of how you got that answer

It’s a. The reason is because Beth makes a stable income for her first 20hrs of work, and then gets another constant income for her coming hours. That said this has to be a straight line followed by another straight line. That narrows it down to a and b. It can’t be b, because if it were Beth would be making less than she did before after her pay changes. Because she makes more, the graph showing this must be a

No because if you do the higher number minus the lower number you will get a positive. if you do it the other way around you will get a negative number