Answer:
18a^2
Step-by-step explanation:
Multiply the numbers together. Multiply the variables together.
(-3a)(-6a) = (-3) * (-6) * a * a = 18a^2
-3 times -6 = 18 since negative times negative is positive, and 3 * 6 = 18.
Also a * a = a^2.
Answer: 18a^2