1. **State the problem:** We are given the function $h(x) = 4x$ and asked to find $h(3)$. 2. **Formula used:** The function $h(x)$ means for any input $x$, the output is $4$ times $x$. 3. **Evaluate the function at $x=3$:** Substitute $3$ into the function: $$h(3) = 4 \times 3$$ 4. **Calculate:** $$h(3) = 12$$ 5. **Answer:** The value of $h(3)$ is $12$. This means when you input $3$ into the function $h(x)$, the output is $12$.