word question

Question

_{Tom and Jack are at opposite ends of an 18km bush track. They both start walking along the track at the same time and meet after 3 hours.
Tom walked at x km/hr. Find an expression in terms of x for the speed at which Jack walked.}

Answer 1

D=rt

The distance Tom walked can be expressed as 3x, so the distance the Jack walked is 18-3x.  This makes the expression 18-3x=3r, where r is the rate Jack walked.  So r=(18-3x)/3 = 6-x.