I have graduated from high school, so I just need to review my math. It is enough to pick it up again in half a year and study for 3-4 hours every day.

What does college mathematics mean? If it's a math department, I'm afraid it will take 5-6 years. If it's just a compulsory math subject except the math department in ordinary colleges and universities, it can be done in three years. It usually takes 3-4 hours. 80 points is a higher level of learning, such as 80 points in calculus.