Given: Distance 1 (D1) = 75 kms Speed 1 (S1) = 15 kmph Distance 2 (D2) = 165 kms Speed 1 (S2) = 33 kmph (v) Distance 3 (D3) = 120 kms (vi) Speed 1 (S3) = 15 kmph Concept: By using average speed formula solve it. By using speed formula find the time for each. Formula Used: Average speed (S) = Total distance/Total Time Time (T) = Distance (D)/Speed (S) Calculation: ⇒ Average speed (S) = Total distance/Total Time ⇒ S = (D1 + D2 + D3)/(T1 + T2 + T3) ⇒ T1 = 75/15 = 5 hr ⇒ T2 = 165/33 = 5 hr ⇒ T3 = 120/15 = 8 hr ⇒ S = (75 + 165 + 120)/(5 + 5 + 8) ⇒ S = 360/18 ⇒ S = 20 kmph ∴ Hence, Average speed of entire travel is 20 kmph.