The best first step to solve the equation \( ax - 7 = 26 \) is to add 7 to both sides of the equation. This will help isolate the term involving \( x \) on one side.
So the correct response is: add 7 to both sides of the equation.
This yields:
\[ ax - 7 + 7 = 26 + 7 \]
which simplifies to:
\[ ax = 33 \]