Step 1 :Let the price per slice be x and the number of slices sold be y. We know that if x = 2, y = 20, and if x = 2 - 0.25, y = 20 + 5.
Step 2 :Using these two points, we can find the equation of the line relating x and y: y = 60 - 20x.
Step 3 :To maximize the revenue, we need to find the value of x that maximizes the product of x and y (R = xy).
Step 4 :R = x(60 - 20x).
Step 5 :Taking the derivative of R with respect to x, we get: R' = 60 - 40x.
Step 6 :Setting R' equal to 0, we find the critical point: x = 1.5.
Step 7 :\(\boxed{1.50}\) is the price per slice that maximizes the revenue.