estimating the yield curve

hi sir.... i am having difficulties in understanding the solution to this question Example A government has three bonds in issue that all have a face or par value of $100 and are redeemable in one year, two years and three years respectively. Since the bonds are all government bonds, let’s assume that they are of the same risk class. Let’s also assume that coupons are payable on an annual basis. Bond A, which is redeemable in a year’s time, has a coupon rate of 7% and is trading at $103. solution Bond A: $103 = $107 x (1+r1)-1 r1 = 107/103 – 1 = 0.0388 or 3.88% in the solution it did not take into account the power of negative 1. why was it omitted when arriving in the answer sir can you kindly help me understand how the formulae can be solved taking into consideration the power of negative 1 when solving the formulae thank you so much in advance