I thought of a 2-digit number. It's a multiple of 9 and the sum of its digits is five times smaller than the number itself. What is my number?

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