1. The problem statement, all variables and given/known data 2. Relevant equations D = rt 3. The attempt at a solution I let d to be the total distance d/3a = t1 ----- time taken for 1st part of the trip d/3b = t2 ----- time taken for 2nd part of the trip d/3c = t3 ------ time taken for the whole trip with uniform speed Since t1+t2 =t3 d/3a + d/3b = d/3c Multiplying both sides by 3abc bcd + acd = abd Dividing both sides by d bc + ac = ab Factoring out c and diving both sides by it. 1/c = (a + b)/ab = 1/a + 1/b 1/c = 1/a + 1/b not the same as 2/c =1/a + 1/b Do you think it is just a typo?