Answer:
x = 18
y = 54°
Explanation:
m<MON = 90° (given)
m<MOA = 72° (given)
m<AON + m<MOA = m<MON (Angle Addition Postulate)
m<AON + 72° = 90° (Substitution)
Subtract 72° from each side
m<AON = 90° - 72°
m<AON = 18°
m<AOD = 18° + 2x
m<BOC = 3x
m<AOD = m<BOC (vertical angles)
18 + 2x = 3x (Substitution)
Subtract 2x from each side
18 = 3x - 2x
18 = x
x = 18.
72° + y + 3x = 180° (angles on a straight line)
Plug in the value of x
72 + y + 3(18) = 180
72 + y + 54 = 180
126 + y = 180
Subtract 126 from both sides
y = 54