Let F be a function of two variables, defined by F(K, L) = 4 Ink + 4 In L. (a) Find RLK = F1'(K, L) / F2'(K, L), the marginal rate of substitution of L for K. (b) Find LK = Elp, (L/ K), the elasticity of substitution between L and K along a level curve for F