Question 96888
(600/x)+(400/(x-20))=35 ... multiply by x(x-20) ... 600(x-20)+400(x)=35x(x-20)


600x-12000+400x=35x^2-700x ... 35x^2-1700x+12000=0 ... 7x^2-340x+2400=0


factoring gives (7x-60)(x-40) ... so x=40 and x=60/7


60/7 results in a negative night speed, which is not realistic