Please Excuse My Dear Aunt Sally.
The strict hierarchy of math steps: Parentheses, Exponents, Multiply/Divide, Add/Subtract.
Standardized to ensure that 2 + 3 x 4 always equals 14, not 20, anywhere in the world.
Multiplication and Division are tied (Left to Right). Addition and Subtraction are tied (Left to Right).
In Plain English: Math has grammar. You can't just read left-to-right. You must handle the powerful stuff first (Groups and Powers) before the weak stuff (Adding).
In The Real World: Coding. If a programmer types `total = cost + tax * discount` without parentheses, the computer calculates tax * discount first!
Always doing Multiply before Divide. They are equals! If you see 10 / 2 * 5, you do the division first because it's on the left.