In the following figure, a train is used for material handing in the shop floor and is moving in the direction of the arrows from left to right. The actual weight of each car $($in $K_B)$ is labeled on the corresponding car as shown on the cars. The train passes through a short tunnel, which contains precisely three complete cars at a time. The weighing device on the floor of the tunnel forecasts the weight of each incoming car through the weight of the cars already inside the tunnel.

What would be the forecast of the weighing device for train car B$?$