<PRE><B>Question 931101</B>
60 miles at speed x mph

40 miles at (x-5) mph

Total time = 8 hours

time first leg + time second leg = 8

t=d/r

60/x + 40/(x-5) = 8

multiply equation by x(x-5)

60(x-5)+40x = 8x(x-5)

60x-300+60=8x^2-40x

8x^2-140x+300=0

/4
2x^2-35x+75=0

2x^2-30x-5x+75=0

2x(x-15)-5(x-15)=0

(x-15)(2x-5)=0

x= 15 OR x=5/2

5/2 is not possible

so speed = 15 mph</PRE>