Answer:
a = 70 degrees
b = 20 degrees
c = 20 degrees
Explanation:
First, we can find "c":
angleBCA = 90
angleBCA = angleBCD + c
90 = 70 + c
90 - 70 = c
20 = c
Knowing "c", we can find "a".
angleADC = 90
triangleADC = 180
triangleADC = angleADC + c + a
180 = 90 + 20 + a
180 = 110 + a
180 - 110 = a
70 = a
Knowing "a", we can find "b".
angle BCA = 90
triangleACB = 180
triangleACB = angleBCA + a + b
180 = 90 + 70 + b
180 = 160 + b
180 - 60 = b
20 = b