please help i cannot figure this out.

For the equations below, q is the total number of units produced per day by m employees of a manufacturer, and p is the price per unit at which the q units are sold. Find the marginal-revenue product for the given value of m. 500m - m q = 50 , P= -0.3q + 90; m = 40 The marginal-revenue product when m = 40 is . (Type an integer or a decimal.) 50 = 6 60- 50 ave