we know that
the sum of the internal angles=(n-2)*180°
where
n=4 (quadrilateral)
the sum of the internal angles=(4-2)*180°------> 360°
the sum of the internal angles in a quadrilateral is 360 degrees
so
360°=∠1+∠2+∠3+∠4
∠1=90°
∠2=90°
∠3=122°
∠4=?
360=90+90+122+∠4
360=302+∠4
∠4=360-302
∠4=58°
the answer is
58°
