C 7/Eb
The C 7 chord consists of the C (Perfect unison), E (Major third), G (Perfect fifth) and Bb (Minor seventh) notes, with Eb as the bass note.

How to play the C 7/Eb chord
- Play Eb as the lowest bass note in the left hand
- Find C (Root) on the piano keyboard
- Add E (Major third) — 4 semitones above C
- Add G (Perfect fifth) — 7 semitones above C
- Add Bb (Minor seventh) — 10 semitones above C
- Press all 5 notes simultaneously to sound the C 7/Eb chord