Why do people get rude at me if I can’t figure out a homework problem?

His style of delivery was impatient because, by 17, the majority of high school students do know how to do this type of equation.
Because of this, he may have regarded it as laziness to be asking for help.
But maybe, for some reason, you might have missed out on learning the method when everyone else did.
However, the method will be there in your textbook.
And there are instructions available free on the internet.
If, after making some serious efforts to do this by yourself, you still can't manage it, It might be worth asking your parents to pay for a weekly coaching session to help you catch up.
Or the school may have a remedial class where you could get one on one help.

He gave you the method for solving the problem when he said to solve the numbers between the parentheses first. But when he said "then divide, multiply, add or subtract", he should have said "then apply the functions given outside the brackets, and follow them in order from left to right.

It's actually very important to learn how to apply the right processes for each type of problem. It's how we learn how to think. Like learning to play music, it cannot happen without practice, and lots of it.
Learning requires effort. It cannot be spoon fed.

I always hated math.

As I investigate your posts, the main lesson you need to learn is to treat people the way you would want them to treat you. This is called the "golden rule." You are upset when others treat you harshly. Others are upset when you treat them harshly.

I was never academic at your age. Some people are really academic some people are really clever in other ways academic people aren’t.

Because they hate the problem, but don't love to solve and/or to help.

I teach mathematics. I agree that that was rude.

That is very rude 😟 Was it a teacher who said that?