What is the most important concept to understand on the SAT reading section?
The most important concept is how to read for the answers and not simply read for comprehension. You don't need to understand the entire article to be able to answer the questions and in fact taking the time to understand a piece is likely counterproductive to improving your score!
How do I improve my score on the science section of the test?
The best way to score well on the science section of the test is to cut down the length of text that you need to analyze on each question. Often, there will be a page of text but the actual relevant question material is likely one or two sentences. I can help you practice how to identify the relevant question more efficiently than you currently are!
Assuming there are 3 variables, x,y,z. 2x^2 + 12y = z where x = 2 and y = 1 what is z?