Top number on your left image should read "-90" or "270".
I don't really understand what your problem is. If you are trying to increase the angle by 90 degrees (or rotate it 90 degrees clockwise), you can simply add 90.
Set Sprite angle to (Sprite.angle+90)
This might give you a result which will be greater than 360, but the system will convert it to correct angle.
Or you can use anglerotate expression:
endAngle=anglerotate(startAngle, startAngle+90, 90)