Trevor is saving up to buy a boat that is going to cost him $90,000. He has $30,000 today at time 0 , and expects to have another $30,000 at time 1 (that is, one year from now). How much should he save at the end of year 2 if he wants exactly $90,000 for the boat at the end of year 3? Assume Trevor can earn an interest of 5% per year on his savings