If you would like to calculate (a^3 - 2 * a^2) - (3 * a^2 - 4 * a^3), you can do this using the following steps:
(a^3 - 2 * a^2) - (3 * a^2 - 4 * a^3) = a^3 - 2 * a^2 - 3 * a^2 + 4 * a^3 = 5 * a^3 - 5 * a^2
The correct result would be 5 * a^3 - 5 * a^2.
