If a < b < 0, which of the following is the greatest number?
B) - ( a + b )
Multiplying an inequality by a negative number changes the direction of the inequality, so multiplying a < b < 0 by 1 gives 0 < b < a. Since b is positive, (a + b) = a + (b) > a. Therefore, the ordering of the five choices is a < 0 < b < a < (a + b), and (a + b) is the greatest. excerpted from The Official SAT Question of the Day