IronFox

In mathematics and computer programming, the order of operations is a collection of conventions about which arithmetic operations to perform first in order to evaluate a given mathematical expression.

These conventions are formalized with a ranking of the operations. The rank of an operation is called its precedence, and an operation with a higher precedence is performed before operations with lower precedence. Calculators generally perform operations with the same precedence from left to right,[1] but some programming languages and calculators adopt different conventions.

https://en.wikipedia.org/wiki/Order_of_operations

With math, you can invent your own notation if you like. If it makes it easier to describe certain problem. This is done often. And if it makes sense, you can also change the order of operation. You can even introduce new operations.

The notation you learn in school is just a common one, but other notations are equally valid and can be useful.

Therefore this kind of question is not a pure math question, but rather it depends on what kind of conventions or notations people want to use.

The context is what allows the math question to have a single answer. The notation is just your chosen way towards that solution and to communicate the steps to that solution to others.

The rules of math itself are much more fundamental and they don’t care about how people decided to write formulas down.

Those aren’t ‘rules of maths’, because math would work with other orders of operations as well. They are conventions. Other cultures could have different conventions and it would work as well.

I don’t get why these kind of post crop up so often.

The answer to them doesn’t matter and these aren’t really math questions, because there is no context given. This is just endless discussions about different people having different assumptions on notation used there…

In real math, where the numbers mean something, good and consistent notation is important, but not necessary, because the order of operations or what those operations are exactly would be clear through the context of these formulas. Good notation just makes it easier to spot errors, work with formulas or to avoid confusion.

Here is what I would assume this formula could mean. Someone has 2 apples and 5 bags of apples that initially came with 8 apples each inside, but someone else ate 5 apples from each of these bags.

With this context it is pretty clear what the answer would be.