R1R2=125\frac{R_{1}}{R_{2}}=\frac{1}{25}R2R1=251
R1R2=5\frac{R_{1}}{R_{2}}=5R2R1=5
R1R2=15\frac{R_{1}}{R_{2}}=\frac{1}{5}R2R1=51
R1R2=25\frac{R_{1}}{R_{2}}=25R2R1=25
