[tex]\left\{\begin{array}{ccc}4x-y=7\\4x-2y=2&\text{change the signs}\end{array}\right\\\underline{+\left\{\begin{array}{ccc}4x-y=7\\-4x+2y=-2\end{array}\right}\qquad\text{add both sides of the equations}\\\\.\qquad\qquad \boxed{y=5}\\\\\text{Put the value of y to the first equation:}\\\\4x-5=7\qquad\text{add 5 to both sides}\\\\4x=12\qquad\text{divide both sides by 4}\\\\\boxed{x=3}\\\\Answer:\ \boxed{x=3\ and\ y=5}[/tex]
