Does greater mean add or subtract?

add

____________________

It depends on the context. 'Greater' is a relationship, not an operation. Add is an operation that means to take two or more quantities, regardless of their relative size, and find the sum of them. 'Greater' indicates that the specified term has a quantity that is more than the quantity of some other term. The fact alone that you are establishing or discovering this relationship does not indicate that you are required to add anything to either one.

On the other hand, the statement "Make 7 greater by 5" means add 7 and 5 together. But the terms 'greater', 'greater than', 'greater than or equal to', are more typically used in the context of relationship above.