4 times a number added to 8 times a number equals 36 Let a number be an arbitrary variable, let us call it x. 4 times a number: 4x 8 times a number: 8x We add these together: 4x + 8x = 12x We set 12x equal to 36 to get our final algebraic expression of: 12x = 36 If the problem asks you to solve for x, you type this algebraic expression into our search engine and get: x = 3