Ok i know this is hard but once you get it you will be fine. -2 is the y value in the order of pair (0,-2). So in the equation y=5x-b plug -2 into y (so that would be -2=5x-b). Then 0 is the x value in the order of pairs so plug 0 into x. ( So -2=5×0-b. start by combining terms, so multiply 5 and 0 such is p. So you are left with -2=-b. I am not completly sure but I don't think you y value can be negative so just flip all the signs and you are left with 2=b!