In This article, A refers to the foreseeable future worth of the expenditure; P refers to the principal total being invested; r refers back to the level of interest; n refers to the number of times the desire receives compounded every year; t refers back to the tenure (in decades) https://www.google.com/maps/d/u/0/viewer?mid=1o3vHoDG_5EIkMXyD_8nuLLiHqxZbkJg