Well firstly, a term, if you don't know this already, is any part of the equation/expression that has a + or - sign on both sides of it. So an expression that is 2x+4z-5xz has 3 different terms.
Now, when looking for like terms, you only focus on the variables/letters that are in each term. It doesn't matter what number is in each term, but it matters if they have the same letters or not. If they have the same letters/variables, then they are like terms.
So out of your terms 7c, -7d, 7cd, -12cd
the only two terms within those 4 that have EXACTLY the same variables/letters are 7cd and -12cd.
Answers & Comments
Verified answer
Well firstly, a term, if you don't know this already, is any part of the equation/expression that has a + or - sign on both sides of it. So an expression that is 2x+4z-5xz has 3 different terms.
Now, when looking for like terms, you only focus on the variables/letters that are in each term. It doesn't matter what number is in each term, but it matters if they have the same letters or not. If they have the same letters/variables, then they are like terms.
So out of your terms 7c, -7d, 7cd, -12cd
the only two terms within those 4 that have EXACTLY the same variables/letters are 7cd and -12cd.
Therefore your answer is B)
I hope this helps!!
-Rachel