a$.$ Assuming that the required return does remain at $18\%$ until maturity, find the value of the bond with $(1)15$ years, $(2)12$ years, $(3)9$ years, $(4)6$ years, $(5)3$ years, $(6)1$ year to maturity.

b$.$ All else equal, when the required return differs from the coupon rate and is constant to maturity, what happens to the bond value as time passes? Explain in light of the foliowing graph:

a$.(1)$ The value of the bond with $15$ years to maturity is $ $($Round to the nearest cent$)$