Question

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.

Answer 1

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