A bomber and fighter

Question

A bomber Takes off and flies at 500 kph. A fighter, setting out 2 and a half hours later flies at 750kph. How long will it take for the fighter to catch the bomber, and how far will the bomber have travelled at this time? Show working please. Thank you. 

Answer 1

Let B = the time bomber flies, then (B - 2.5) = the time the fighter flies and

500B = 750(B-2.5), i.e. each plane flies the same distance.

Multiply and collect terms: 250B = 1875 => B = 7.5

The fighter catches up in B-2.5 = 5 hrs.

The bomber will have traveled 500B = 3750 miles.