两个式子相减：23% - 13% = (Rf + 1.3×(Rm-Rf)) - (Rf + 0.6×(Rm-Rf))，化简得10% = 0.7×(Rm-Rf)，解得Rm-Rf = 14.2857%。代入第一个式子：23% = Rf + 1.3×14.2857%，得Rf = 4.43%，再代入Rm = Rf + 14.2857% = 18.71%。