a car moves in a straight line at 22.0 m/s for 10.0miles, then at 30.0 m/s for another 10.0miles. calculate the car’s average speed in m/s

The average car speed is  25.4 m/s

Explanation:

The definition of average speed is the total distance traveled between the total time

     Vm = dx/dt        (1)

To be able to use this equation let's calculate the total carriage distance

     Xt = X1 + X2

     X1 = 10 miles 1609  m / 1 miles = 16090 m

     X2 = 10 miles 1609 m / 1miles = 16090 m

     XT = 32180 m

Now let's calculate the total time

      v = d / t

      t = d / v

      t1 = x1 / v1

      t2 = x2 / v2

      t1 = 16090/22

      t1 = 731.36 s

      t2 = 16090/30

      t2 = 536.33 s

      t all = t1 + t2

      t all = 731.36 +536.33

      t all = 1267.69 s

Having these values we use the initial equation

      Vm = d / t

      Vm = 32180 /1267.69

      Vm = 25.38 m / s

The average car speed is   25.4 m/s