The answer is already given in your question. The inverse of a function f is f-1, g is g-1, h is h-1 and i is i-1.
To explain why the inverse of <span>f = {(1,2), (2,3), (3,4), (4,5), (5,6), (6,7)} is f-1 = </span><span>f -1 = {(2,1), (3,2), (4,3), (5,4), (6,5), (7,6)} and that of the other functions to their corresponding inverses is because of the definition of the inverse of a function which is f = (x, y) f-1 = (y, x)
Simply, the x and y coordinates of a function are interchanged to get the inverse of the function.</span><span />
Set up a ratio 3 3/4 = 15/4 and 1 1/2 = 3/2 so ((15/4miles) / (3/2hours)) = xmiles/4hours solve for x so x = 4hours*((15/4miles)/(3/2hours)) = x miles the hours cancel and you are left with x miles = 10miles