Question

Let f(x)=12/4x+2 fine f(-1)

Answer 1

F(-1)
it's easy. instead of x we will put -1 and we will calculate the value 
SO
f(-1)=12/4*(-1)+2
f(-1)=12/-4+2
f(-1)=12/-2
f(-1)=-6

Answer 2

$f(x)= \frac{12}{4x+2 }$

$For f(-1) =\ \textgreater \ x =\ \textgreater \ -1$

$f(-1) = \frac{12}{4.(-1) + 2}$

$f(-1) = \frac{12}{(-4) + 2} = \frac{12}{-2} = -6$

$f(-1) = -6$