Explanation:
here's your solution
==> angle AGE = 30°. [ Given ]
==> angle DGC = 90°
==> angle AGE = angle FGC. [ vertical angle ]
==> so, angle FGC = 30°
==> angle ( BGF + FGC + DGC ) = 180°. [ linear pair ]
==> 90° + 30° + x° = 180°
==> x° = 180° - 120°
==> x° = 60°