$\begin{array} { l }2x-7=1,\\2x-7=-1\end{array}$
Solve the equation for $x$$\begin{array} { l }x=4,\\2x-7=-1\end{array}$
Solve the equation for $x$$\begin{array} { l }x=4,\\x=3\end{array}$
The equation has $2$ solutions$\begin{array} { l }x_1=3,& x_2=4\end{array}$