Answer:

the average speed =27.69m/s

Explanation:

let y m be the total distance

case1 } y/4m(d)

speed=10m/s

time1* =y/40

case2 } y/6m(d)

speed =15m/s

*time2=y/90

average speed =total distance /total time

average speed =y /time1+time2

avg .speed= y/time

time1 +time2= 13y/360

avg speed =y×360/13y

avg speed=360/13

avg speed =27.69m/s

hey mate here is ur answer ✌✌hope it helps you...