This might seem dumb,but: How do i improve in math?

あなた don't. Trust me I know. I've been trying since middle school and I still can't get over a D on tests.

We're allowed to use calculators at my school :c and I am in normal math. If I wasn't allowed to use a calculator I would probably be screwed. I really wish I could help あなた but I honestly don't know what to say. Practice maybe?

Constantly ask ur teacher 4 help even if they don't want 2 give it! That is wat I have done 4 the last few years now!

あなた and the other students could sign a petition and/or complain to administrators I guess. If the whole class didn't finish, または the majority, that's not fair, especially if あなた were an A B student, because apparently あなた know it.

I think あなた need to complain about your teacher to someone at your school. She sounds extremely unfair and probably needs a talking-to.
The way to improve maths is to revise.

Alternate Testing! If あなた can't finish a test in time tell your guidance counselor and they might put あなた in the Alternate Testing room when あなた write tests and stuff and they will give あなた extra time especially if not being able to finish cause あなた a lot of stress. That is what most schools around here are like anyway.

If the class can't finish the entire test, then she is being completely unfair. Math tests should ONLY be 与えられた a number of problems that the average time it takes for the class to finish plus a few もっと見る minutes, that way there's no excuse for not finishing the test in time. She needs to get rid of some of the problems on the test to fit the necessary time または allow calculators. It seems like she's a horrible teacher. Its hard to improve times in math unless you're a g-ness または something, but even then math follows rules and steps that あなた can't always skip. The only way あなた can improve in math is like other classes, study and do problems over and over again until あなた got the pattern down.

あなた 発言しました yourself, "The only reason I failed is because we weren't 与えられた enough time". So it might not be that あなた need to improve, but to have もっと見る time on the tests. 45 分 sounds very short on time for a test so if your teacher won't do anything tell the principle/headteacher (or whatever あなた call it where あなた are).
I had an exam a week 前 and it was 2 hours even though we all usually finish within the first hour. The point is 45 分 is way too short for a test in my opinion...