1. **State the problem:** We are given the function $f(x) = 5x - 7$ and need to evaluate $f(3)$. 2. **Recall the formula:** The function $f(x)$ means for any input $x$, the output is calculated by multiplying $x$ by 5 and then subtracting 7. 3. **Substitute the value:** Replace $x$ with 3 in the function: $$f(3) = 5 \times 3 - 7$$ 4. **Calculate step-by-step:** $$f(3) = 15 - 7$$ 5. **Simplify:** $$f(3) = 8$$ 6. **Final answer:** The value of $f(3)$ is 8.