Write down the decimal expansion of the rational number $\frac{6}{15}$.

(N/A) To find the decimal expansion of the rational number $\frac{6}{15}$,we first simplify the fraction by dividing both the numerator and the denominator by their greatest common divisor,which is $3$.
$\frac{6}{15} = \frac{2 \times 3}{5 \times 3} = \frac{2}{5}$.
Now,we convert $\frac{2}{5}$ into a decimal by dividing $2$ by $5$:
$2 \div 5 = 0.4$.
Thus,the decimal expansion of $\frac{6}{15}$ is $0.4$.