import numpy as np
px = np.linspace(55,110)
dx = 3.777178e6*px**(-2.154)
profit = (px-50)*dx

import matplotlib.pyplot as plt
plt.figure(figsize=(6,4))
plt.subplot(2,1,1)
plt.plot(px,dx,label='Demand')
plt.plot(price,d.value[0],'o',markersize=10,color='orange')
plt.grid(); plt.ylabel('Demand'); plt.legend()
plt.subplot(2,1,2)
plt.plot(px,profit,label='Profit')
plt.plot(price,obj,'o',markersize=10,color='orange')
plt.grid(); plt.legend()
plt.xlabel('Price'); plt.ylabel('Profit')
plt.tight_layout(); plt.savefig('results.png',dpi=300)
plt.show()