Which relation is a function?
a. {(-3, 8), (9, -12), (0, 0), (4, -1)}
b. {(4,5), (4, - 7), (4,2), (4,9)}
c. {(8, 4.5), (-2, 1.2), (5,0.3), (-2, 1)}
d. {(-6,-4), (-2, -, -1)}

Out of the 180 students at a summer camp, 72 signed up for canoeing. there were 23 students who signed up for trekking, and 13 of those students also signed up for canoeing. use a two-way table to organize the information and answer the following question: approximately what percentage of students signed up for neither canoeing nor trekking? 72% 40% 54% 98%