If 50% of a number is 20, which is 75% of what number

If i have one apple and give you the apple, how many apples do i have?

Just tell me how to set up the 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