Question 897423
You have two columns.
x and f(x)
Think of f(x) as y
Think of f(-4) as find y when x=-4
So look in the x column for -4 and you will find -3 so y =-3 which means  f(-4)=-3
-4	-3

f(2) 
find f(x) when x=2 or find y when x=2 
2	12
For what value of x is f(x)=7?
means find x when y=7
so look in the f(x) or y column for 7 and find x
0	7