I need to know the steps to solve (63,64,65,66) the most important is (65,66). Please provide a complete solutions for all the questions and in detail. Thank you in advance

63. Find the first partial derivatives of the following function. 4s - t f(s,t) = 2s + 3t f = ft = 64. Find the first partial derivatives of the following function. f ( x, y) =13x + 8 xy+ yz fx = fy = 65. Find the first partial derivatives of the following function. f ( x , y ) = 5x By f = fy = 1 66. Find the first partial derivatives of the following function. UV h (u, v ) = 2u - 5v hu (u, v) = hy ( u , v ) = 6