Question 103245

{{{x-y=4}}}     from equation {{{x = y + 4}}} substitute this value of {{{x}}} in second equation
{{{y=2-x }}} = > {{{y = 2 – (y + 4)}}}
                 {{{ y = 2 – y – 4}}}
                  {{{y + y = -4}}}
                  {{{2y = -4}}}
                    {{{y = -2}}}

now substitute {{{y = -2}}} in {{{x-y=4}}}    and find {{{x}}}
{{{x-y=4 }}}    
{{{x-(-2)=4 }}}
{{{x + 2 = 4}}}
{{{x = 4 – 2}}}
{{{x = 2  }}}