2. $\frac{f + 3}{12}=\frac{7}{2}$

Explanation:

Step1: Cross - multiply

$2(f + 3)=7\times12$

Step2: Expand the left side

$2f+6 = 84$

Step3: Subtract 6 from both sides

$2f=84 - 6$ $2f = 78$

Step4: Divide both sides by 2

$f=\frac{78}{2}$

Answer:

$f = 39$