59. When G(x,y) = x3 - y' - 3x + 4y, there is a critical point at a. (0,1) b.(0,-2) c. ( -1,2) d. (0,2) e. (0,0) 60. At a beach cafe, the profit made from selling x ice creams and y popsicles in a certain time period is P(x.y) = 25x + 10y-x - + w dollars . For function has one critical point and it is a maximum. Find the number of icecreams sold to maximize this profit. a. 11 b. 18 c. 20 d. 22 e. 12 61. How many saddle points in the following contourplot a. 1 b. 2 c. 3 d. 4 e. 5