Hi Gerry,

I am going to reword your question to add some notation.

A delivery driver travels from Belfast to an address in Dublin.The total distance for the round trip was 2d kilometres .The time required for the forward trip was f hours. Due to heavy traffic during the return trip an extra e hours was required. How much slower was the delivery drivers speed on the return trip?

I made the total distance 2d kilometers because I am assuming it is d kilometers each way.

Since distance = time rate I know that on the forward trip

rate = d/f kilometers per hour

The return trip took f + e hours so on the return trip

rate = d/(f + e) kilometers per hour

Thus the return trip was d/f - d/(f + e) kilometers per hour slower than the forward trip.

I hope this helps.
Penny