The equation is 

             (Subtract 7 from each side)

                         (Apply Additive inverse property: 7 7= 0)

                                (Subtract:    )

Check:

To check the solution, substitute  in original equation.

                               (Add: 7 + 14 = 21)

The statement is true.

 Graph the solution on number line.

\
• First draw a number line.
\
• Mark a dot at 14 on  the number line.
\

The value of .