50 points if you can ! ~urgent~ the function f(x) varies directly with x and f(x)=3 when x=12. what is the value of f(x) when x=40? a. 160 b. 4 c. 10 d. 480

I do this a little differently then mostbut if it varies directly, then I make a proportionand f(x) is the same as y

3/12 = y/40
cross multiply
(12)(y) = (3)(40)
12y = 120
y = 120/12
y = 10 < so f(x) or y = 10