Answer:
x = 16
Step-by-step explanation:
The diagram can be misleading because angle A does not correspond to angle F. Rather angle F corresponds to angle C.
In congruent triangles, corresponding angles have the same measure. The sum of angles is always 180°, so we have ...
... m∠A +m∠B +m∠C = 180°
... (3x+6)° +50° +(9x -68)° = 180°
... 12x -12 = 180 . . . . . divide by °, collect terms
... x -1 = 15 . . . . . . . . . .divide by the coefficient of x
... x = 16 . . . . . . . . . . . add 1
_____
Check
m∠A = (3x+6)° = 54°
m∠C = (9x -68)° = 76°
The total of angles is 54° +50° +76° = 180°. . . . . as it should be
