Question

If m∠2 = 108° and m∠P = 55°, then m∠O = ?

Answer 1

Is there a figure?

Answer 2

You can go about this 2 ways.
1) The sum of the measures of the angles of a triangle is 180.
Since you know m<2 = 108, and <1 is supplementary to <2, you can find the m<1. You are given the measure of <P.
m<1 + m<P + m<O = 180
Solve the equation for m<O.
2) The measure of an exterior angle of a triangle is equal to the sum of the measures of the remote interior angles.
<2 ia an exterior angle. <P and <O are remote interior angles, so
m<P + m<O = m<2
You know the measures of angles P and 2, so solve for m<O