please solve with steps

-11. The return provided by Treasury bonds is considered as risk-free return and provides a basis to compare the return offered by corporate bonds. Refer to Figure 14.3, which shows yields to maturity for corporate bonds for different maturities and default ratings. Calculate the spread to Treasury for a BBB-rated bond for two years and for seven years. Why do the bonds with same credit rating offer different spread to Treasury for different periods? Rivise 4 A.3 Corporate Bond Yelofis flond Yields by Bond Rasting and Term to Matarity