the formula of constant speed is:

x=Vt

We know that the distance is the same: X

First of all he travels the distance of X with the speed of 600, so: X=600t1

Then it travels the distance of X with the speed of 400, so: X=400t2

Now we can say that the total distance is 2X and the total time taken is

X/600 + X/400= 5X/1200

So as to find the average speed we should divide the total distance by the total time taken: 2X÷5X/1200=480

1 Like