Which of the following relations is a function?

a {(2, 2), (3, 3), (4, 4), (5, 5)}
b {(2, 1), (2, 3), (3, 6), (3, 7)}
c {(3, 5), (4, 9), (4, 11), (5, 14)}
d {(4, 8), (6, 6), (8, 4), (8, 2)}

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. x^2 - 23 = 10x a. -1.93, 11.93 b. 1.93, -11.93 c. 1.93, 11.93 d. -1.93, -11.93

Use multiples to write two fractions equivalent to 7/9. 14/18, 8/10 6/8, 21/27 10/12, 28/36 14/18, 21/27