resolve this problem !!!!!?

a train is made of two carriages ( the first one has 100 tones and the second one 10 tones). the train is moving with a constant speed and on a straight line. at one time, the second carriage separate and moves 10 km before it stops. how many km does the train move(the first carriage in the same time as the second carriage)? g=10m/sˆ2