In a class of 450 students, 300 are taking a mathematics course and 260 are taking a science course. If 140 of these students are taking both courses, how many students are not taking either of these courses?

(1) 30 (3) 110

(2) 40 (4) 140

I know there is a formula or equation for"EITHER"questions such as this one.

What is a good formula or equation to use to find the answer?