Answer:
B: -34
Step-by-step explanation:
The given angles are supplementary, so you have ...
(2x+146) + (4x+238) = 180
6x +384 = 180 . . . . . simplify
6x = -204 . . . . . . . . . subtract 384
x = -34 . . . . . . . . . . . .divide by 6
_____
Check
angle F is (2·(-34)+146)° = 78°
angle C is (4·(-34)+238)° = 102°
These angles indeed are supplementary, so the answer checks OK.
