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
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