polynomials addition

Question

 

(12a²b²c-6abc²-9a²b²c-3abc)+(8a²b²c-4abc²-10abc+5a²bc²)

Answer 1

This requires you to know about like terms.  The same variable and the same power means you can add those terms together.  For example,  12a^2b^2c  and  8a^2b^2c will get 20 a^2b^2c.