Before we can solve this word problem, we have to translate first this problem into numerical form. The sum of fifteen and six times a number t is 81 can be translated into 15 + 6t = 81 We can now solve this equation. Let's add both sides of the equation by -15. 15 + 6t - 15 = 81 - 15 6t = 66 Divide both sides of the equation by 6. 6t / 6 = 66 / 6 t = 11