Here is your answer
REASON :
We know that the angle subtended by an arc at the centre is twice the angle subtended at the remaining part of the circle.
So,
m(arcAC)= 28 degree
Using above relation, we get
m(arcAC)= 2×/_ADC
/_ADC= m(arcAC)/2
/_ADC= 28/2
/_ADC=14 degrees
[NOTE:- m(arcAC) is same as the angle subtended at centre]
HOPE IT IS USEFUL