For the Vans store in the Temecula Mall, the wecky profit, in dollars, of selling x shoes is P(x)=0.006x30.2x2+900x1200, and currently 60 shoes are sold weckly. a) What is the current wockly profit? b) How much profit would be lost if the shoe store were able to sell only 59 shocs weckly? c) What is the marginal profit when x=60 ? d) Use marginal profit to estimate the weekly profit if sales increase to 61 shoes weekly.