import numpy as np
import matplotlib.pyplot as plt
px = np.linspace(55,110)
dx = 3.777178e6*px**(-2.154)
profit = (px-50)*dx
plt.figure(figsize=(6,3))
plt.plot(px,profit)
plt.plot(price,obj,'o',markersize=10,color='orange')
plt.grid(); plt.xlabel('Price'); plt.ylabel('Profit')
plt.tight_layout()
plt.show()