the answer is 72.8. in order to solve this problem, you need to use the pythagorean theorem. the equation is c^2-b^2=a^2.
75^2-18^2=a^2
75 squared minutes 18 squared is 5301. then you need to find the square root of 5301.
the square root of 5301 is 72.8079666, rounding to 72.8.