Which phrase is commonly used to indicate addition in mathematics?

The phrase "all of the above" is correct because each of the phrases listed can indicate the operation of addition in mathematics, though they may be used in slightly different contexts.

"Greater than" does not directly indicate addition itself but rather describes a relationship between two quantities. However, the phrases "increased by" and "combined" explicitly refer to processes that involve the addition of numbers. For example, "increased by" is often used when discussing how much one number is added to another to achieve a new total. Similarly, "combined" is commonly used in word problems to indicate that two or more quantities are being added together.

Therefore, recognizing that these phrases can point to the operation of addition demonstrates a comprehensive understanding of mathematical language.