Sample math problems are available online via Washington State University and Algebra.Help. Washington State University offers college level sample problems while Algebra.Help offers more intermediate level problems.
Washington State University offers 36 online sample problems. The concepts are listed beside each one; these link to detailed explanations of the concept and step-by-step solutions.
Algebra.Help offers two or three sample problems per concept. Each sample has the problem stated and the answer right below. Clicking on a concept brings up a page that contains more problems. A step-by-step is offered for each problem, and answers are available online and on a printable sheet.