Answer
72°
Explanation:
sum of angles of a triangle= 180°
Let, the value of the unknown angle in the triangle be y°
Therefore,
30° + 42° + y° = 180°
or,
72° + y° = 180°
or,
y° = 180° - 72°
or,
y° = 108°
We know that a straight line = 180°
here, AM is a straight line (A till the arrow sign of the line is a straight line, you should have named the last point of the line drawn)
Therefore,
y° + x° = a straight line = 180°
we have known before that, y° = 108°
108° + x° = 180°
x° = 180° - 108°
x° = 72°