C 5/G#
The C 5 chord consists of the C (Perfect unison) and G (Perfect fifth) notes, with G# as the bass note.

How to play the C 5/G# chord
- Play G# as the lowest bass note in the left hand
- Find C (Root) on the piano keyboard
- Add G (Perfect fifth) — 7 semitones above C
- Press all 3 notes simultaneously to sound the C 5/G# chord