Question 338672
Given D =1.2√h, solve for h.

D/1.2 = √h

[D/1.2]^2 = [√h]^2

D^2/1.44 = h

============================

To answer 2(b), let h = 14,255 and solve equation for D.  I'll let you do that.

============================

To answer the second part of 2(b), convert 89 miles to feet (one mile equals 5280 feet) and then replace D with your conversion to solve for h.

I'll let you do that.