Final answer:
A Perfect Fifth above Fb is Ci.
Step-by-step explanation:
A Perfect Fifth is an interval that is 7 semitones or half steps apart. To find a Perfect Fifth above Fb, we start with Fb and move up 7 semitones. In music theory, Fb is enharmonically equivalent to E, and going up 7 semitones would give us a note that is 7 half steps above E, which is Ci.