Evaluate: 7f+3+6=-28

Expression: $7f+3+6=-28$

Add the numbers

$7f+9=-28$

Move the constant to the right-hand side and change its sign

$7f=-28-9$

Calculate the difference

$7f=-37$

Divide both sides of the equation by $7$

$\begin{align*}&f=-\frac{ 37 }{ 7 } \\&\begin{array} { l }f=-5 \frac{ 2 }{ 7 },& f=-5.\overset{ \cdot }{ 2 } 8571\overset{ \cdot }{ 4 } \end{array}\end{align*}$