March 1st SAT?

Hi. I'm a sopre and I'm taking theSAT next week. I would normally wait until junior year to take it, but I'm applying to this magnet high school, and they require you to take the SAT. I got a 58,49, and 63 on critical reading, math, and writing respectively on the PSAT. I'm concerned about the math portion because it has geometry and algebra in it. I haven't taken geometry since the 8th grade, and algebra since the7th. I know how to answer the algebra II questions though. Also, I can't write an essay in 25 minutes. I'm a good writer, according to my GT coordinator and my English teacher. In fact, I just got a 75 out of 50 (no typo) for an essay comparing Julius Caesar to todays politics. I just can't write an essay that fast. Any pointers?