Solving and Checking Absolute Value Equations

Concept: http://www.brightstorm.com/math/algebra/absolute-value/absolute-value-equations/
Problem 1: http://www.brightstorm.com/math/algebra/absolute-value/absolute-value-equations-problem-1/
Problem 2: http://www.brightstorm.com/math/algebra/absolute-value/absolute-value-equations-problem-2/
Problem 3: http://www.brightstorm.com/math/algebra/absolute-value/absolute-value-equations-problem-3/
Problem 4: http://www.brightstorm.com/math/algebra/absolute-value/absolute-value-equations-problem-4/