Answer: 4a - 2ba, also written as 4a - 2ab.
Explanation:
1. Mulitply (a-b) with (a+2) using the FOIL method, in which you would multiply a with a, a with 2, -b with a, and -b with 2. After multiplying that you would get a^2 + 2a -ba -2b.
2. Mulitply (a+b) (a-2) using the FOIL method, in which you would multiply a with a, a with -2, b with a, b with -2. After multiplying that you would gett a^2 + 2a -ba -2b.
3. Now, simplify a^2 + 2a -ba -2b - a^2 + 2a -ba -2b by combining like terms. This should give you 4a - 2ba, also written as 4a - 2ab.