Consider this sentence:<br/><br/> Existing firms in the industry increase <b>quantity of</b> output because marginal revenue now intersects maginal cost at a higher <b>quantity of</b> output. <br/><br/>But why is the word "quantity" needed when we could just say: <br/><br/> Existing firms in the industry increases output because marginal revenue now intersects maginal cost at a higher output.