Answer :

what remains exceeds[To find how much something exceeds you subtract] 17 - f×12 -
one-third of seventeen 
17 - f×12 -1/3 
×17 by six. 17 - f×12 - 1/3 ×17 = 6
17 - 12f - 17/3=6 
Multiply through by 3 to avoid fractions: 51 - 36f - 17 = 18 34 - 36f = 18 -36f = -16
f=-13/-36
simplify: f= 4/9