2x + 2y = 6 . . . . . (1)
x + 3y = -1 . . . . . (2)
(1) x 3 => 6x + 6y = 18 . . . . . (3)
(2) x 2 => 2x + 6y = -2 . . . . . (4)
(3) - (4) => 4x = 20
x = 20/4 = 5
Find a combination calculator, but in 14 and 4, choose combinations (not permutations) and you will see the number
For a triangle to be a triangle all the angles have to add up to 180 degrees. So 52 degrees plus 28 degrees would equal 80. So now to find the answer 180 - 80 then your final answer is 100! Hope This Helps