import numpy as np

qs = np.arange(80)

def profit(q): 
  return 40 * q - 0.5 * q**2


profits = profit(qs)
max_profit = profits.max()

max_ind = np.argmax(profits)
q_opt = qs[max_ind]


print(f"The optimum is {q_opt} pieces of furniture, which makes ${max_profit} profit.")

The optimum is 40 pieces of furniture, which makes $800 profit.