A truck weighing W1 = 4000 lbs. pulling a W2 = 20 ton trailer is stalled on a 30 ft long bridge W3 = 8000 lbs. (1 ton = 2000 lbs.) Consider the weight of the bridge at its center. The truck is stalled at a distance of 10 ft from the left end and the trailer is 20 ft from the left end. Find the forces on the left end F1 and on the right end F2 of the bridge.