Some friends decide to go camping for the weekend. they cannot all fit in one car so some of them catch a bus to the campground, which is 510kilometers from home. those in the car started driving at 8 am and arrived at the campground at 3: 30 pm, driving at a constant speed. the bus also drives at a constant speed and takes the same route as the car. its distance in kilometers (y) from home x hours after leaving is given by the equation y=78x. determine the speed of the bus, in kilometers per hour.

formula: speed=distance/time
distance =y

time =x