Reading 37 CFAI Q#4 pg 168 first, 168, understand, increase, question

leadcfa

In this question I don’t understand where the “appropriate forward rate” of 7.0024% came from for the first year or 8.007% in the 2nd year. All it says is that they increase the overpayments by the “appropriate forward rate”, but where does this come from?

bpdulog

(1+r2)^2/(1+r1) - 1
1.065^2/1.06 - 1 = 7.0024%
1.07^3 / 1.065^2 - 1 = 8.0071%