Can someone help me with this math homework please!

Which expressions equal 9 when x=4 and y=1/3 a. x2+6y b. 2x + 3y c. y2-21x d. 5 (x/2) -3y e. 3x-9y

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?

Prove the converse of the pythagorean theorem using similar triangles. the converse of the pythagorean theorem states that when the sum of the squares of the lengths of the legs of the triangle equals the squares length of the hypotenuse, the triangle is a right triangle. be sure to create and name the appropriate geometric figures.