One car travels 40 km/hr faster than another. While one travels 150 km, the other goes 350 km. Find the speed of the slower car.

So the speeds are s and s+40

distance=speed times time

if we assume the time is the same, and it is t

350 = (s+40) (t)

and

150 = (s) (t)

so

350=st+40t

150=st

multiply 2nd equation by - 1 and add to first

350=st+40t

-150=-st +

200=+0st=40t

200=40t

divide both sides by 40

5=t

so

speed=disatnce/time

s=150/5

s=30

slower car is 30mph