Question 1085787
Since the distance varies as the square of the speed, we can express this relationship as:
d = k*s^2 where k = a constant
For two sets of distances and speeds (d1,s1) and (d2,s2) we can write
d1 = k*s1^2 and 
d2 = k*s2^2
Thus d1/s1^2 = d2/s2^2 -> d2 = d1*(s2/s1)^2
Putting in the values, we have
d2 = 30*(28/20)^2 = 58.8 ft