When using PEMDAS it states that addition comes before subtraction.
Why is it that the 0 + 1 is not done first and then finally the 6 - 1 ?
That's the part that confuses me lol
Addition and subtraction are at the same level, and are done from left to right. Subtraction is really just the addition of a negative number, much like division is just multiplication by the reciprocal (multiplicative inverse).
So, in an expression like you posted, where there are no bracketing symbols (parentheses, etc.) and no exponents, we first do the multiplication/division from let to right, then we do the addition/subtraction from left to right. Multiplication and division have the same precedence as do addition and subtraction.