A car travels from Calabar to Enugu, a distance of p km, at an average speed of u km/h, and continues to Benin, a distance of q km, at an average speed of w km/h. Find its average speed from Calabar to Benin.
Worked solution (try it first)
Time is distance over speed: the two legs take up and wq hours.
Add them over the common denominator uw: total time =uwwp+uq.
Average speed is total distance over total time: (p+q)÷uwwp+uq=wp+uquw(p+q), option C.