if f(x) varies directly with x and f(x) = 4 when x = 12, then what is the value of f(x) when x = 60?

20
180
5
300

what is the domain of the function: {(2, 1); (4, 2); (6, 3); (8, 4)}?

{6, 8}
{1, 2, 3, 4}
{1, 2, 3, 4, 6, 8}
{2, 4, 6, 8}
what is the turning point of the graph of f(x) = |2x| – 3 ?

(–2, –3)
(0, 0)
(0, –3)
(2, 0)