Using the calorie information provided in the table below, a protein bar has 250 total food calories from protein, fat, and carbohydrate. If the bar contains $p$ grams of protein, $f$ grams of fat, and $c$ grams of carbohydrate, which of the following expresses $p$ in terms of $f$ and $c$?

Macronutrient	Food calories	Kilojoules
Protein	4.0	16.7
Fat	9.0	37.7
Carbohydrate	4.0	16.7