A 14 oz box of candy will contain 84 grams of fat.
Explanation
A 3.5 oz box of candy contains 21 g of fat.
Lets assume, a 14 oz box of candy will contain [tex]x[/tex] grams of fat.
Now using the ratio of 'weight of the box' to the 'grams of fat' , we will get.....
[tex]\frac{3.5}{21}=\frac{14}{x}\\ \\ 3.5x=21*14\\ \\ 3.5x= 294\\ \\ x=\frac{294}{3.5}=84[/tex]
So, a 14 oz box of candy will contain 84 grams of fat.