Answer:
F / g = 138 kg
Explanation:
For this exercise let's use Newton's second law
  F- W = m a
the force is equal to the back of the balance
in this case the acceleration is centripetal
  a = v² / r
we substitute
  F - m g = m v² / r
  F = m (g + v²/ r)
calculus
  F = 80 (9.8 + 11²/17)
  F = 1353 N
the balance reading is this value between gravity
  F / g = 1353 / 9.8
  F / g = 138 kg