4. which relation is a function?
a.
{(8, –1), (2, –1), (3, 8), (2, 5}
b.
{(1, 2), (1, 5), (1, –1), (1, 4)}
c.
{(–3, 4), (–2, 5), (0, 9), (0, 12)}
d.
{(7, 12), (1, –5), (3, –10), (2, –5)}

Rick is driving to his uncles house in greenville,which is 120 miles from ricks town .after covering x miles rick she's a sign stating that greensville is 20 miles away. which equation when solved will give the value of x. a: x+120 = 20 b: x x120 =20 c: x +20 equals 120 d: x x20= 120