You just got a job and plan to save for the college expenses for your kids. You have a son and a daughter. Your son is 4 years old, and your daughter is only 1 year old. Both of them plan to go to a four-year college at the age of 18. The estimated college expense is about $40,000 per year. Assume you plan to invest into a portfolio that offers you return about 6% per year until your daughter is graduated from college. How much money do you need to save every year if your first saving is in one year? please show all steps and use formulas and not financial calculator