Question 313460
{{{1/Rt=1/R1+1/R2+1/R3}}}
{{{1/R2=1/Rt-1/R1-1/R3}}}
{{{R2=1/(1/Rt-1/R1-1/R3)}}}
{{{R2=Rt*R1*R3/(R1*R3-Rt*R3-Rt*R1)}}}