Why this is right?

Due to the brevity of the short term, costs can be both fixed and variable. As aresult, firms always attempt to boost their revenues. In the long run, fixedcosts are nothing more than variable costs. Profit margins are considerably increased when costs are kept low.Businesses do not have to operate on a single average cost curve in the shortterm as long as all expenses vary over time. In other words, long-term costs arecalculated by adding up short-term costs (SRACs), each of which represents adifferent amount of fixed costs. No matter how much output is produced, the long-term average cost curve will be the most affordable. Those experiencinginefficiencies in their output should brace themselves for their business models'probable extinction.