Judy and Jill leave Jill's house at the same time. Judy drives north and Jill drives west. Judy's average speed is 6mph slower than Jill's.

Question

At the end of one hour, they are 85 miles apart. Find Jill's average speed.

Answer 1

about 63 mph for Jill's speed

about 57 mph for Judy's speed

in one hour Jill goes 63 miles

Judy goes 57 miles

57^2 + 63^2 = 85^2. It's a right triangle, where sum of sides squared = hypotenuse squared