Exercise 13.2.8 Assume that one unit of domestic(foreign) currency grows to R

(Rf, respectively) units in a period, and u and d are the up and the down moves of the domestic/foreign exchange rate, respectively. Apply identity (13.7) to derive the risk-neutral probability [ (R/Rf)−d ]/(u−d) for forex options under the BOPM in Exercise 11.5.4, part (1).