Answer:
x = 9
Step-by-step explanation:
(13x + 2) + (5x -7 ) + (3x-4) = 180°( sum of angles in a triangle)
13x + 2 + 5x - 7 + 3x - 4 = 180
13x + 5x +3x + 2 - 7 - 4 = 180
21x - 9 = 180
add 9 to both sides
21x - 9 + 9 = 180 + 9
21x = 189
Divide through by 21
x = 9
