Equation 9-2: There are six variables in this equation: "net proceeds per bond," "cost of debt capital or kb," "interest paid in year 1," "interest paid in year 2," "interest paid in year 3," and "principal." To do what the text is describing, which variable is solved for absolutely last?

(9-2) Net proceeds per bond + interest paid in year 2 cost of debt 1+ capital or kb 2 interest paid in year 1 cost of debt 1+ capital or kb interest paid in year 3 cost of debt 1+ capital or ky + + + 3 principal cost of debt 1+ capital or kb