Khan Academy
SAT Prep: Test 2 Section 6 Part 2
Reviewing the last problem from the previous video because he feels that he "rushed it," Sal again explains the concept of ratios as it applies to problem 6 on the practice SAT (page 472 in The Official SAT Study Guide). Additional...
Khan Academy
Khan Academy: Multiplying and Dividing Negative Numbers
A video showing the rules of multiplying and dividing negative numbers.