Three of four numbers have a sum of 22. if the average of the four numbers is 8, what is the fourth number? don't just answer, tell me how to answer. i think i just need setting up the correct equation

Use the formulas a = x 2 – y 2, b = 2xy, c = x 2 + y 2 to answer this question. one leg of a right triangle has length 11 and all sides are whole numbers. find the lengths of the other two sides. the other leg = a0 and the hypotenuse = a1