import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-10, 10, 100)
y1 = 5x
y2 = -5x

plt.figure()
plt.plot(x, y1, label='y=5x')
plt.plot(x, y2, label='y=-5x')
plt.legend()
plt.xlabel('x')
plt.ylabel('y')
plt.title('Graph of y=5x and y=-5x')
plt.grid(True)
plt.axhline(y=0, color='k')
plt.axvline(x=0, color='k')
plt.show()