**1. The problem statement, all variables and given/known data**

A car races past a pedestrian crossing at 20 m s-1 (which is well in excess of the speed limit); 10 seconds later a police car travelling at 30 m s-1 passes the pedestrian crossing in pursuit of the offender. Assuming that both cars maintain constant speeds, how far from the crossing will the police car catch the speeding car?

**2. Relevant equations**

I was thinking I would use x=vt (‘x’ being displacement) and solve using a simultaneous equation

**3. The attempt at a solution**

Speeding car:

x=20*t

Police car:

x=30*(t+10)

x=30t+300

I’m not sure where to go from here

http://ift.tt/1lnB3HL