<PRE><B>Question 1029152</B>
A biker decided to cover the distance of 120 km at a certain speed.

let speed be x

Time he would take = 120/x ( t=d/r)

 However, he actually went 6 km/h slower
Actually his speed was 6 km slower (x-6)

Time taken =120/(x-6)


 so he arrived at his destination 1 hour later

120/(x-6) -120/x = 1

Simplify

120x -120(x-6) = x(x-6)

120x -120x +720=x^2-6x

x^2-6x-720=0

x^2-30x+24x-720=0

x(x-30)+24(x-30)=0

(x-30)(x+24)=0

x= 30 OR -24

Ignore negative

planned speed = 30 km/h</PRE>