如果利率为10％。那么明年支付15美元，以后每年支付10美元的无限期债券，它的价格应是多少？如果利率提高到15％，它的价格应该是多少？为什么？ What is the price of a bond that pays$15 next year and then$10 per year indefinitely if theinterest rate is 10 percent？What would it be if the interest rate rises to 15 percent？Why？