To multiply fractions, we simply multiply the numerators together and the denominators together.
Hence, (-2/5) * (3/10) = (-2 * 3) / (5 * 10) = -6 / 50.
To simplify the fraction, we can divide both the numerator and denominator by their greatest common divisor, which is 2 in this case.
Therefore, (-6/50) รท 2 = -3/25.
The final answer in simplest form is -3/25.