Assuming that the original speed of the car is x km/h and the distance between Party A and Party B is y km, then

y/x( 1+20%)+ 1 = y/x( 1)

120/x+(y- 120)/x( 1+25%)+40/60 = y/x(2)

Y=6x can be found in (1).

Then substitute y=6x into (2)

The solution is x=45.

y=6x=270