Let R(s, t) = G(u(s, t), v(s, t)), where G, u, and v are differentiable, and the following applies. U ( 2 , - 4 ) = -2 v(2, -4) = 4 Us (2, -4) = -5 VS ( 2 , - 4 ) = 1 U . ( 2 , - 4 ) = 8 V+ ( 2 , - 4 ) = -9 Gu( -2, 4) = 3 G ( -2, 4) = 5 Find R (2, -4) and R.(2, -4). R s ( 2 , - 4 ) =