The slope-intercept form is y=mx+b, where m is the slope and b is the y-coordinate of the y-intercept, so we can already conclude that b=-1.
This results in y = mx - 1
We also have the x-intercept, and we know that the y-coordinate of an x-intercept is always 0. This means that we have the point (4,0). Substitute this into the formula to generate m:
Base in your diagram which shows the top view of a prism sitting upright on one of its trapezoid bases and the height of the prism is 10cm. The surface area base on my calculation is 124cm^2. I hope i answered your question correctly