Question 137179
{{{A=Ra/(R+a)}}}
{{{A(R+a)=Ra}}}
{{{AR+Aa=Ra}}}
{{{AR+Aa-Ra=0}}}
{{{AR-Ra=-Aa}}}
{{{R(A-a)=-Aa}}}
{{{R=-Aa/(A-a)}}}
{{{R=Aa/(a-A)}}}