Displacement = 1/2(Initial Velocity + Final Velocity)Time
If we plug in the values (0 as initial velocity, 12.5 as final velocity, 7 as time), we get 43.75 meters.
According to the given condition we are 137 meters behind the origin. That would mean our initial displacement is -137 meters. After driving for 7 seconds, the car would be 43.75 meters closer to the origin.
-137 + 43.75 = - 93.25 meters (or 93.25 meters behind the origin).