If a, b and c are non-zero, a + 1/b = 1 and b + 1/c = 1, then the value of abc is?

∵ a + 1/b = 1
ab + 1 = b ...(i)
Also, b + 1/c = 1
⇒ b = 1 - 1/c ...(ii)
From Eqs. (i) and (ii), we get
ab + a = 1 - 1/c
⇒ ab = -1/c
⇒ abc = -1