Answer: 38 degrees
Explanation:
Because arc AB is equal to 76 degrees, angle ADB must also be 76 degrees.
Then simply take the supplement of the angle to get that < CDA is 104 degrees. Because it is part of an isosceles triangle, simply subtract 104 from 180 to get that <A + <C = 74 degrees. Because triangle ADC is isosceles (All radii of a circle are equal), simply divide 76 / 2 to get that <C = 38.
Hope it helps :)