Final answer:
The proof is based on the definition of supplementary angles, which must sum to 180°. Since angle 1 is 68°, angle 2 must be 180° - 68°, which equals 112°.
Step-by-step explanation:
The question requires us to prove that the measure of angle 2 (m2) is 112° less than 180°, given that angle 1 (m1) is 68° and that angles 1 and 2 are supplementary. By definition, supplementary angles add up to 180°. Therefore, if m1 is 68°, m2 must be 180° - 68° so that together they sum to 180°.
Here is the calculation: 180° - 68° = 112°.
Thus, m2 = 112°, completing the proof.