Answer:
In the equation f(x)=6x <--- that x is the independent variable.
Explanation:
The independent variable changes freely
f(x) would be the dependent variable because it depends on the independent variable.
ex.
You're going to the movies with your friends. Each tickets costs 6 dollars (from the 6 in the equation above). You are bringing 5 friends with you, that's what the independent variable is. Your total, or f(x), will be 35.