The generally accepted convention for order of operations is to do all operations within parenthesis first followed by exponential notation, multplication then division (left-to-right), and addition and subtraction from left-to-right.
The acronym PEMDAS (Please Excuse My Dear Aunt Sally) was designed to help students remember this conventional 'order'as they simplified expressions: parenthesis - exponents - multiplication - division - addition - subtraction.
A similar acronym, BEMDAS (Brackets Exponents Multiplication Division Addition Subtraction) is the same thing but with the B exchanged for the P for parenthesis.
An acronym that I prefer is GEMA (Grouping Exponents Multiplication Addition). Now, why did I not include division and subtraction in my acronym? It's simple~we are always using the inverse of these operations when simplifying expressions in pre-algebra so it is a 'given,' as far as I am concerned so why nit-pick over a letter or two? You should have this ingrained by now and the acronym is simply to help remind you that order matters.