1. The problem is to solve the equation $12 = f + 7$ for $f$. 2. To isolate $f$, subtract 7 from both sides of the equation. 3. Write the subtraction step: $$12 - 7 = f + \cancel{7} - \cancel{7}$$ 4. Simplify both sides: $$5 = f$$ 5. Therefore, the solution is $f = 5$. This means that when $f$ is 5, the equation $12 = f + 7$ holds true.