Choose the best definition for the following phrase: combining like terms.

Choose the best definition for the following phrase: combining like terms.

 A letter that holds the place for some unknown value in mathematics.

 A process where you must look for terms that have identical variable parts and then combine their coefficients.

 A process where if two things are equal, one can be put in the place of the other and nothing will change.

 Terms that have identical variable parts.