A futures contract: the maturity date T, the current time t, the current price of the underlying asset S, the execution price K, the risk-free interest rate R. The present value of dividend income generated by the underlying asset is I. The risk-free interest rates is 10%.

(1) Suppose the present value of the dividend income of the underlying asset is I, write the calculation formula of the theoretical value f and price F, and deduce it by the combination setting.