What is the sum of all four-digit numbers formed by using all digits 0, 1, 4, 5 without repetition of digits?

Which among the following is NOT a corner point of the LPP, maximize Z = 4x + y subject to the constraints $$x + y \le 50, 3x + y \le 90, x \ge 0, y \ge 0 ?$$​​

Which among the following is NOT a corner point of the LPP, maximize Z = 4x + y subject to the constraints $$x + y \le 50, 3x + y \le 90, x \ge 0, y \ge 0 ?$$​​