Question

Two trains a and b are moving with speeds 20 m/s and 30 m/s respectively in the same direction on the same straight track, with b ahead of a. The engines are at the front ends. The engine of train a blows a long whistle. The speed of sound in still air is 340 m/s. The speed of the sound of the whistle is

Answer 1

Answer:

oh it's very hard to understand