You need to pay for 4 years of tuition starting 15 years from now. The tuitions are 35000, 37000, 39000, and 42000 respectively. You plan to save a fixed fraction of your salary starting at the end of this year, and ending with the last tuition payment in 18 years. At 6% interest, starting with your salary of 85000 this year and a 3.2% salary increase per year, calculate the fraction of your salary to be saved. The first tuition payment is at the end of year 15.