Answer:
Step-by-step explanation:
the sum of the interior angles of a triangle is 180°
so
9x + 3 + 11x - 21 + 5x - 2 = 180
25x = 180 - 3 + 21 + 2
25x = 200
x = 200 : 25
x = 8
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E = 9 * 8 + 3 = 75°
D = 5 * 8 -2 = 38°
F = 11 * 8 - 21 = 67
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check
75 + 37 + 67 = 180°
