Question 132608
{{{s=a/(a-r)}}} Start with the given equation



{{{s(a-r)=a}}} Multiply both sides by {{{a-r}}}



{{{sa-sr=a}}} Distribute



{{{sa=a+sr}}} Add {{{sr}}} to both sides



{{{sa-a=sr}}} Subtract "a" from both sides



{{{(sa-s)/s=r}}} Divide both sides by s to isolate r



{{{r=(sa-s)/s}}} Rearrange the equation