Suppose that the treasurer of IBM has an extra cash reserve of $100,000,000 to invest for six months. The six-month interest rate is 9 percent per annum in the United States and 7 percent per annum in Germany. Currently, the spot exchange rate is 0.88 per dollar and the six-month forward exchange rate is 1.23 per dollar. The treasurer of IBM does not wish to bear any exchange risk. Where should he/she invest to maximize the return? Use equations to explain your answer.