two planes are traveling in the same direction and at the same altitude such that one plane is 64.2 miles ahead of the other. the distance between the two planes is 85.7 miles. to the nearest tenth of a mile, what is the distance, d, between the two flight paths?

I believe that in this problem, we are asked for the hypotenuse of the triangle that can be formed when we make a right triangle out of the planes and the intersection of their paths. To solve for the hypotenuse of a right triangle, we make use of the equation,
                                   h² = 64.2² + 85.7²
The value of h from the equation is equal to 106.0 miles. 

Area of B =80

I hope it's helps you