The expression 3 -42 + 6 / 2 was evaluated what would be done first

The correct answer should be squaring.

This is because of the order of operations. It says that all grouping should be done first (parentheses, absolute value, brackets, etc.). This expression doesn't have any of those.

Next is exponents. This expression has a square so it should be done first.
After that, we do multiplication and division in order from left to right.
Lastly, we do addition and subtraction, also in order from left to right.