Add: 2a3 + 5a - 7 and 5a2 - 6a + 12

So for this you are adding like terms

that means 5a and - 6a are added together and would come to - 1a or - a.

-7 and 12 added together would be 5.

2a^3 and 5a^2 dont have like terms so they stay like so.

final answer would be 2a^3+5a^2-1a+5