A company insures homes in three cities, X, Y, and Z. Since sufficient distance separates the cities, it is reasonable to assume that the losses X, Y, and Z occurring in these cities are mutually independent The moment generating functions for the loss distributions of the cities are: Mx(t) (1-2t)-25, My(t) (1 2t)-3, Mz(t)( 2t)-3.5 Let U represent the combined losses from the three cities: U X + Y + Z. a. Calculate E[U] b. Find the joint moment generating function of X, Y and Z: Mxyz(s, t, w).