Question 58105
Use the definition of slope:
{{{slope=rise/run}}}

When you have two points ({{{x[1]}}},{{{y[1]}}}) and ({{{x[2]}}},{{{y[2])}}}),
Rise = {{{y[2]-y[1]}}} and Run = {{{x[2]-x[1]}}}.

Using the information from the problem, we have:
{{{slope=rise/run}}}
{{{2=(7-3)/(x-4)}}}
{{{2=4/(x-4)}}}
{{{(x-4)*2=4/cross(x-4)*cross(x-4)}}}
{{{(x-4)*2=4}}}
{{{(x-4)=2}}}
{{{x=6}}}