The percent of change is 9%
You want to start by subtracting 5 from both sides to get 2/3x=-8/3 then cross multiply to get whole numbers which is 6=-24x then your gonna want to isolate the variable so divide both sides by -24 to get 6/-24=x then you can simplify to x=-1/4
40mph for Car B I think. 45mph for Car A. 45(mph) times 4(h) is 180(distance) and 40 times 4.5 is also 180. Sorry if I'm wrong.