I got a few problems like this one. The only thing I can't figure out is where to put the km. Here's what I got. A car traveling 95km/hr is 100m behind a truck traveling 75km/h. How long will it take the car to reach the truck. My 2 formulas are: X=Xo+Vo+(1/2)at2 Car: X=95t2 Truck: X=75t2 Put both formulas equal to each other and solve for t. But where do I plug in the 100m that the car is behind? Thanks.