Answer:
Part 1:
Angle DCB is a right angle.
So, angle DCA + angle ACB = 90
Angle ACB = 90 - angle DCA = 90-50=40
Answer is option C. 40
===========================
Part 2:
Angle DCB is a right angle.
So, angle DCA + angle ACB = 90
Angle ACB = 90 - angle DCA = 90-60=30
Answer is option B. 30