7. Suppose we take out a loan and agree to repay it with payments of $160 after one year, $180 after two years, and $400 after four years. The loan in renegotiated so that we make a single payment of $740 at time T and this results in the same present value of payments when calculated using an annual effective rate of 5%. (a) Estimate T using the method of equated time. (b) Find T exactly (you may need some kind of numerical solver, for example, Wol- fram Alpha)