Let q denote the output of a single firm and Q the output of the entire industry.A supply function for a firm gives the firm's profit-maximizing level of output q as a function of the market price p.An industry supply function indicates how much output Q all the firms in the industry will produce at the market price p.If there are 20 perfectly competitive firms and each of them has the supply function q = p / 5then what is the industry supply function?