Step-by-step explanation: What I'd do first is set the question up as an ordered pair, for example (x,y) have the uniforms be represented by x and the cost be represented by y. We know that the cost of five uniforms is $66, so we can substitute (x,y) into (5,66). We can then do the same for nine uniforms which is 105 (9,105). The equation we are going to use to find the slope is y2-y1/x2-x1 = 105-66/9-5.
This should result in 39/4. Make sure to always simplify when needed, in this case we don't have to.
