Need help homies, no steps needed

Complete the solution of the equation. find the value of y when x equals to 28 x+3y=28

Simplify (4x^2 - 8xy + 2y^2) - (9x^2 - 4xy - 7y^2) a. -5x^2 + 4xy + 9y^2 b. -5x^2 - 4xy + 9y^2 c. -5x^2 + 12xy + 4y^2 d. -5x^2 - 4xy - 5y^2

The given diagram shows the parts of a right triangle with an altitude to the hypotenuse. using the two given  measures, find the other four.