Which of the sets of ordered pairs represents a function?

a = {(−5, 5), (−2, 2), (2, −2), (5, −5)}

b = {(4, 2), (3, −2), (9, 4), (11, −3)}

Agarden consists of an apple tree, a pear tree, cauliflowers, and heads of cabbage. there are 40 vegetables in the garden. 24 of them are cauliflowers. what is the ratio of the number of cauliflowers to the number of heads of cabbage?

Sawsan recorded the favorite sport of students at her school. she surveyed 200 students. how many students chose tennis?

What is the period of the sinusoidal function ?