The tube in a heat exchanger has a 2-in. inner diameter and a 3-in. outer diameter. the thermal conductivity of the tube material is 0.54 btu/h∙ft∙℉, while the inner surface heat transfer coefficient is 50 btu/h∙ft2∙℉ and the outer surface heat transfer coefficient is 10 btu/h∙ft2∙℉. determine the overall heat transfer coefficients based on the outer and inner surfaces.