Suppose that the yields of a 1-year, 2-year, 3-year, 4-year, and 5-year bonds are 3%, 3.5%, 4%, 4.5%, and 5%, respectively. The price of a one-year forward contract starting in year 4 to year 5 is 7.0. If the entire term structure shifts down by 1%. Re-price the one-year forward contract starting in year 4 to year 5.

The answer is 6.0 but I need the step-by-step answer. Thanks!