First, undo the division of 6 by multiply both sides by 6.
Then undo the subtraction by adding 5 to both sides.
[tex]\frac{(f-5)}{6} = 4\\(6)\frac{(f-5)}{6} = 4(6) \\f-5 = 24\\ +5 = +5\\f = 29[/tex]