Is it true that on this site a+b/c+d means (a+b) / (c+d)?

It's not so much that people don't know their order of operations but that they don't know the proper use of the symbol /. The horizontal bar in a rational expression is used to represent division but is also a grouping symbol. When people unfamiliar with writing expressions online try to type a rational expression, they type / in place of the horizontal bar not realizing this means division only and is not a grouping symbol. It can't be a grouping symbol as how would you know what is grouped in the numerator and the denominator without parentheses. This probably seems obvious to you and me but to most, it appears it is not.

It still drives me a bit crazy, though, that so many people asking a calculus question can't seem to type things correctly. I've gotten tired of replying to questions by starting with "assuming you mean...." when it seems somewhat obvious that they meant something other than what they typed. I either ignore these questions or answer them based exactly on what they typed instead of second guessing what they meant. Especially if it's a calculus question or some more advanced subject. I just assume someone asking this type of question knows their order of operations and meant exactly what they type.

I also think it's weird when someone answers by saying the question is ambiguous. Per the order of operations it is not ambiguous! That's why we have the order of operations, to avoid ambiguity. It may be typed wrong but it isn't ambiguous.

No, it just means that the majority of people posting questions do not know how to format them correctly. It p*sses me off too. If someone wanting help cannot be bothered to learn how to present an expression properly, why should anyone bother to answer it.

No, by the rules of PEMDAS the division would be carried out first...

a+(b/c)+d=a+b/c+d

And it is not for this site, but by the rules of mathematics...

Rita, don't encourage them....