Question 552057
{{{(7-w)/(9-w) = 2/(w-9)}}}
{{{7-w=2(9-w)/(w-9)}}}
{{{7-w=-2(w-9)/(w-9)}}}
{{{7-w=-2cross((w-9))/cross((w-9))}}}
{{{7-w=-2}}}
{{{-w=-2-7}}}
{{{-w=-9}}}
Multiply by -1 both sides
{{{(-1)(-w)=(-1)(-9)}}}
{{{w=9}}}