Attempt the question, check the explanation, and continue with similar questions to build confidence before exams.
(a + b)(c + d) = ac + bd
(a + b)(c + d) = ac + ad + bc + bd
(a + b)(c - d) = ac - ad + bc - bd
(a - b)(c + d) = ac + bd
Continue with nearby questions to strengthen the same chapter concept while you still have the context fresh in mind.