Answer:
3) m∡ACB = 40 m∡ABC = 63
4) m∡BCA = 14 m∡ABC = 83
Explanation:
Since DE is a line it has 180 degrees so:
103 + CAB = 180
CAB = 77 degrees
All triangle interior angles of a triangle add up to 180 degrees, so:
BAC + ACB + CBA = 180
3x - 14 + 3x + 9 + 77 = 180
6x + 72 = 180
6x = 108
x = 18
Plug in your values:
3(18) - 14 = 40
3(18) + 9 = 63
Use the same method for the next problem.