Question 921633
Your variable description for speeds of car and bus are inconvenient.  Set r as the unknown speed of the bus.  The speed then for the car is {{{-30+2r}}}, or 2r-30 for the car.  The car is going faster than the bus.



__________________speeds__________time__________distance
CAR_______________2r-30___________2_____________{{{(2r-30)*2}}}
BUS_________________r_____________2______________{{{r*2}}}


The distance difference described makes for {{{highlight((2r-30)2-r*2=20)}}}.
Solve for r, which is the SPEED of the BUS.