Question 900824
100/x + 100/(x-30) = 5hr
100(x-30) + 100x = 5x(x-30)
5x^2 -350x + 3000 = 0
x^2 - 70x + 600= 0
(x -60)(x-10) = 0
x = 60mph, speed going
30mph returning
and
 1 2/3 +  3 1/3 = 5hr