Answer:
mAOB = 139 degrees
Explanation:
1) By supplementary angles, you can set up the equation:
mAOB + mBOC = mAOC = 180
8x + 51 + (6x - 25) = 180
2) Solve for x:
14x + 26 = 180
14x = 154
x = 11
3) Substitute x into 8x + 51 to get mAOB:
8(11) + 51
=88 + 51
=139