The first step is to isolate the variable. Y= mX + b
No, you are incorrect. The question is to pick the first step for the elimination method, not the substitution method.
From your note - apparently there is a LOT of confusion.
How so?
Needless complexity that adds no value.
Emphasis on knowing the specific names of methods to solve mathematical problems.
Apparent over-emphasis on the process and not the product.
In fact - viewed from where I sit - this seems to emphasize the need to follow rules more than solve problems. It may seem small - but it is indicative of a larger cultural issue.