A student has to sell 2 books from a collection of 6 math, 7 science, and 4 economics books. How many choices are possible if
(a) both books are to be on the same subject?
(b) the books are to be on different subjects?
A student has to sell 2 books from a collection of 6 math, 7 science, and 4 economics books. How many choices are possible if
(a) both books are to be on the same subject?
(b) the books are to be on different subjects?