# Pls solve the first one

Dear student,
Average speed=total distance travelled/total time taken.
Let the distance between A and B is‘d’.
From A to B:
Let time taken = t1
Then, ${t}_{1}=\frac{d}{60}$ (in hr)
From B to A:
Let time taken = t2
Then, ${t}_{2}=\frac{d}{80}$ (in hr)
Now, total time taken,

Total distance travelled = d + d = 2d
Then, Average speed is

(displcament is zero as the initial point = final point)
hence,
Average speed=68.57 km/hr
Average velocity =0

Regards,

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