Physics Problem HELP!?!?! Probably easy 10pts to right answer! :))?

Two cars travel along a straight road. What t=0, car A is at position xa= 48 km and has a constant speed va= 72 km/h. Later at t=0.4 h, car B is at xb=0km with vb= 100 km/h. At what time will B overtake A? At what position will that occur? How long before B overtakes A? Was A at the Origin? PLEASE SHOW THE STEPS TO SOLVING THESE PROBLEMS (equations, etc) THANKS :)))