Step-by-step explanation: To understand how to combine like terms, let's look at an example.
9c + 2c
The two parts of this expression, +9c and +2c, are called terms. The numbers in front of the variables, +9 and +2, are called coefficients.
Since the variables, c and c, are identical, the two terms in this problem are called like terms.
Like terms can be added together by simply adding their coefficients.
So in this problem, since 9 + 2 = 11, 9c + 2c is simply 11c.