Fx: x is a logic student
Gx: x is ambitious
Hx: x studies hard
Jx: x is an exercise
Kx: x is easy
Fxy: x does y
a: Bob
b: Carol

8. If all the exercises are easy not everyone studies hard. Everyone studies hard, so some of the exercises must not be easy.

JKDHVNC, HV |- JKNE

1. JKDHVNC
2. HV \show JKNE
3. HVJKDNC....1 C subs
4. JKDN.......2,3 C elim
5. JKNE.......4 DN subs