If 4 times a number is added to 9, the result is 49. A number means an arbitrary variable, let's call it x. 4 times a number means we multiply x by 4 4x Added to 9 means we add 9 to 4x 4x + 9 The result is means we have an equation, so we set 4x + 9 equal to 49 4x + 9 = 49 <-- This is our algebraic expression To solve this equation, we type it in the search engine and get x = 10