To multiply two fractions, we simply multiply the numerators together and multiply the denominators together.
In this case, we have (-2/5) * (3/10).
Multiplying the numerators gives us (-2 * 3) = -6.
Multiplying the denominators gives us (5 * 10) = 50.
Therefore, the answer is -6/50.
To simplify further, we can divide both the numerator and denominator by their greatest common divisor, which is 2.
-6 divided by 2 is -3, and 50 divided by 2 is 25.
So, the final simplified answer is -3/25.