I need help right away

The john deere company has found that revenue,in dollars, from sales of heavy-duty tractors is a function of the unit price p, in dollars, that it charges. if therevenue r is r(p)= -1/2p^2 +1900pa)how much revenue will the company generate if they sell 700 tractors? b) how many tractors does the company want to sell to maximize the revenue?

The equation of line e is y  =  -4/9x  +  5/6.  line f is parallelto line e.  what is the slope of line f

Which is the equation of an ellipse centered at the origin with endpoints of major and minor axes at : (0, -7), (0, 7), (-3, 0), (3, 0)?