Explanation:
< PRS = 123°
<QOP = x
Now
< PRS + <QRP = 180° { Being linear pair }
123° + <QRP = 180°
<QRP = 180° - 123°
< QRP = 57°
< QOP = x
= 2 * < QRP < angle at the centre is twice the angle at the circumference >
= 2 * 57°
= 114°
Therefore x = 114°
Hope it will help :)❤