To solve the equation \( 20 = 6x - 4 \), the first step is to isolate the term with \( x \).
The best initial step here would be to add 4 to both sides to eliminate the -4 on the right side of the equation. So, the correct choice is:
Add 4 to both sides.
This will give you:
\[ 20 + 4 = 6x \]
or
\[ 24 = 6x \]
From there, you can solve for \( x \).