4) Simplify. Write your answer using whole numbers and variables. (r)/(3r^2)+r square

To simplify the expression $\frac {r}{3r^{2}+r}$, we can factor out the common factor of $r$ from the denominator.<br /><br />$\frac {r}{3r^{2}+r} = \frac {r}{r(3r+1)}$<br /><br />Now, we can cancel out the common factor of $r$ in the numerator and denominator.<br /><br />$\frac {r}{r(3r+1)} = \frac {1}{3r+1}$<br /><br />Therefore, the simplified expression is $\frac {1}{3r+1}$.