The function P(x) = - 4.75x + 1250x - 6000 gives the profit when x units of a certain product are sold. Find a) the profit when 50 units are sold dollars b) the average profit per unit when 50 units are sold dollars per unit c) the rate that profit is changing when exactly 50 units are sold dollars per unit d) the rate that profit changes on average when the number of units sold rises from 50 to 100. dollars per unit e) The number of units sold when profit stops increasing and starts decreasing. (Round to the nearest whole number if necessary.) units