

The original function is  
   
Write  as
          as  or
          or  
               
First solve the case  .
            .
Apply subtraction property of equality: if a = b, then a - c = b - c.
\ (Subtract 6 from each side)
                                 (Subtract 6 from each side)
 (Additive inerse property:
                                           (Additive inerse property:  )
)
 (Additive identity property:
                                                 (Additive identity property:  )
)
 (Divide each side by negative 2)
                              (Divide each side by negative 2)            
 (Cancel common terms) \ \
                                     (Cancel common terms) \ \
 (Divide:
                                          (Divide:  ) \ \
) \ \
Next solve the case  .
                     .
 (Subtract 6 from each side)
                               (Subtract 6 from each side)
 (Additive inerse property:
                                    (Additive inerse property:  )
)
 (Additive identity property:
                                         (Additive identity property:  )
)
 (subtract:
                                 (subtract:  )
            )            
 (Divide each side by negative 2)
                             (Divide each side by negative 2)            
 (Cancel common terms) \ \
                                    (Cancel common terms) \ \
 (Divide:
                                           (Divide:  )
) 
First, draw a number line.
\To graph the solutions set, mark the numbers 0 and 6 on number line.
\
The solution set is  .
.