Aquadrilateral has 2 right angles the measure of the third angle is 122 ..what is the measure of fourth angle

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°

What the heck i didn’t know