Answer:
36 degrees
Step-by-step explanation:
Since OA and OC are perpendicular, the measures of the two angles will add up to 90 degrees
You can set up this equation to solve for x:
(6x-12) + (3x+30) = 90
Combine like terms
9x + 18 = 90
Solve for x
9x = 72
x = 8
Plug in 8 as x in the equation for angle AOB
6x - 12
6(8) - 12
48 - 12
= 36 degrees