Answer: 4a^2-2b^2 (I think this is right)
Explanation:
Using the order of operations I started by multiplying both of the sides separately. The left side of the equation becomes 2a^2-b^2-ab while the right becomes 2a^2-b^2+ab. Then I put the sides together to add them and after combining like terms it becomes 4a^2-2b^2.