When the price of capital falls, the firm will want to produce more output now that an input price has fallen. When the price of capital falls, for a given level of output, the firm will want to substitute the relatively cheap capital for workers. Therefore, there may be job creation or job destruction as a result of the investment tax credits. It depends upon the relative sizes of the output and the substitution effects. The market for beef is perfectly competitive with constant costs.
Demand shifts down due to the price of chicken decreasing.
This shifts the supply curve left, to the point where the remaining firms make zero profits again.