The difference between the costs is $20 and the difference in the crates is 2 so the slope is 20/2=10, the coefficient for x.
The equation then is y-k=10(x-h) where (x,y) is a pair of values from the table: (2,25), (4,45), (6,65), (8,85). Eliminate answers A and C because the coefficient is -10. Answer D has the (h,k) values the wrong way round, but B is correct in all respects so B is the answer.