Which set of ordered pairs represents a function?

a.{(0, 0), (2, 3), (1, -4), (2, -2)}

b.{(3, -2), (-4, -1), (0, 3), (0, 5)}

c{(-5, 1), (-4, 2), (-5, 3), (-4, 4)}

d{(5, 6), (2, 6), (-3, 4), (-1, 4)}

Sundar used linear combination to solve the system of equations shown. he did so by multiplying the first equation by 5 and the second equation by another number to eliminate the y-terms. what number did sundar multiply the second equation by? 2x+9y=41 3x+5y=36