ANSWER
[tex]f(60)=3\times60=180[/tex]
EXPLANATION
We were given that
[tex]f(x)[/tex]
varies directly as
[tex]x.[/tex]
We can write this mathematically as,
[tex]f(x) \propto \: x.[/tex]
This implies that,
[tex]f(x) = kx[/tex]
where k is the constant of variation.
[tex]f(4)=4k[/tex]
This implies that,
[tex]4k=12[/tex]
[tex]k = 3[/tex]
The equation becomes
[tex]f(x)=3x[/tex]
When [tex]x=60[/tex]
[tex]f(60)=3\times60=180[/tex]
