A bus leaves the stop 30 minutes before the scheduled time. The driver decreases its speed by 30km/hr. At the next bus stop 180 km away, the bus reached on time. Find the original speed of the bus?  Choose the correct option.
A) 110km/hr
B) 120km/hr
C) 130km/hr
D) 140km/hr
E) None of these
Explanation :   Distance = 180km, actual speed = x and actual time = t   180 = x*t   180 = (x – 30)*(t +1/2)   Solve both equation, we will get x = 120km/hr   Answer – 120km/hr
<result>B</result>
A bus leaves the stop 30 minutes before the scheduled time. The driver decreases its speed by 30km/hr. At the next bus stop 180 km away, the bus reached on time. Find the original speed of the bus?