B is the right answer
f(x) = x-3
y= x-3
x= y-3
x+3 =y
f^-1(x) = x+3
I think is 70 because you first sum 18 + 6, then your answer is 24 and you subtract 90 - 24 because the triangle is a right angle that is 90 degrees. That got me 66 and I round it to the nearest tenth and I get 70.
If you walk at a constant speed of x (I will let you determine x) x=step length you will the determine your time per yard... then multiply it by however you get it to 60.