Help me please!!! This is urgent.?

Average speed = distance covered / time.

For the enire trip the average speed is S/ (t1 + t2) = S/ 9 = 50km/h

S = 450 km. -----------------------------1 where t1 is the time taken for the first half distance and t1 is the time taken for the seciond half distance.

For the fist half the average speed is S/ 2t1 = 45 km/h -------------2

For the second half the average speed is S/ 2t2 = V------------------3

From 1 and 2, t1 = 450/ 90 = 5 hours

And so t2 = 4 hours

and from 3, V = 450 / (2*4) = 56.25 km / hour