Tim and Cynthia leave Cynthia's house at the same time. Tim drives north and Cynthia drives west. Tim's average speed is 10mph
10
mph
slower than Cynthia's. At the end of one hour, they are 70
70
miles apart. Find Cynthia's average speed. (Round your answer to the nearest tenth.)
If Cynthia's speed is x mi/hr, then we have
x^2 + (x-10)^2 = 70^2
now just find x