Your 30-year mortgage loan for 500 mil. is made at 4.8% p.a. which is to be paid by equal monthly amount starting at the en d of next month. After 10 years from today, you are going to refinance this mortgage. by that time, how much (%) will be the re maining principal of this (old) mortgage loan? (1) 60%; (2) 63%; (3) 67%; (4) 70 %: (5) 73%; (6) 77%; (7) 80%; (8) 83%; (9) 87%; (10) 90%; nen TITIME P