⇒ Solutions
All the interior angles of a triangle will always add up to 180°. Angle 1 plus angle 6 will equal 180°. If angle 6 is equal to 125° to find angle 1 you will need to subtract 125° from 180°.
180° - 125° = angle 1
180° - 125° = 55°
Angle 1 = 55°
Check your work
To see if the answer is correct 125° + 55° have to equal 180°
125° + 55° = 180°
The answer is correct