1. Bill is 30 years old man earning $80,000 per year. He expects to work till age 65. He desires to have retirement income equal to 80% of pre-retirement income. He plans on 25 years of retirement life. He plans to spend extra $15,000 for vacation during year 70 and leave $25,000 for charity at the end. Assume interest rate is 6%. How much should he save per year during his working years to achieve his plan? If interest rate decreases, will he need to save more or less? Explain.