MRPL is measured by the additional output obtained from the additional unit of this labor,multiplied by the additional revenue from an extra unit of output. Because△R/△L=(△R/△Q)(△Q/△L),it follows that MRPL=(MPL)(MR) In a competitive output market,the marginal revenue from the sale of an additional unit of output is then equal to P. MRPL=P(MPL) MRPL is measured by the additional output obtained from the additional unit of this labor, multiplied by the additional revenue from an extra unit of output. Because R/L= (R/Q) (Q/L), it follows that MRPL = (MPL) (MR) In a competitive output market, the marginal revenue from the sale of an additional unit of output is then equal to P. MRPL = P (MPL)