1. The problem is to solve the equation $30 + f = 16$ for $f$. 2. We use the basic algebraic rule: to isolate $f$, subtract 30 from both sides. 3. Subtracting 30 from both sides: $$30 + f = 16$$ $$\cancel{30} + f = 16 - \cancel{30}$$ $$f = 16 - 30$$ 4. Simplify the right side: $$f = -14$$ 5. Therefore, the solution to the equation $30 + f = 16$ is $f = -14$. Note: The other equations given are variations but the first equation is the one solved as per instructions.