If the length of the freight car is L and the speed is V, then V = (500+L)/28 = (374+L)/22 gives L = 88 and V = 2 1.

Let the bus speed be x, then (L+96)/(V+x)=4 is substituted into (96+88)/(x+2 1) =4 to get x=25.

The bus speed is 25m/s..