M would be equal to 1/2 and be would be equal to b=8. the equation used to find this is m= y2-y1/x2-x1 for m then use a pair of points to solve for b using m.
I think it might be B. 48 due to the fact 18 • 48 = 864. I think it would be easier to figure out if there was a picture to go with it. Don’t take my word for it though. Sorry.