jmc

$$\frac{(304{)}^5}{(29.7)(399{)}^4}\approx \frac{300^5}{30\cdot 400^4}=\frac{3^5\cdot 10^{10}}{3\cdot 4^4\cdot 10^9}=\frac{3^4\cdot 10}{4^4}=\frac{810}{256}$$ Which is closest to $3\to \boxed{3}$. (The original expression is approximately equal to $3.44921198$.)