Answer:
60 km/hr
Step-by-step explanation:
Let the speed at the initial average speed from Town X to Town Y be a.
We are told that it journeyed to Town Z at an average speed 20 km/h faster than its initial average speed. Thus, its average speed here is (a + 20) km/hr.
Town Y was 200 km from Town Z.
Thus, time spent here is;
t_2 = 200/(a + 20)
Time from X to Y is; t_1 = 150/a
We are told that it took the same time to travel for both parts of the journey.
Thus; t_1 = t_2
150/a = 200/(a + 20)
Cross multiply to get;
150(a + 20) = 200a
150a + 3000 = 200a
200a - 150a = 3000
50a = 3000
a = 3000/50
a = 60 km/hr
