class Math:
    def add(self):
        a = 10
        b = 15
        print("Result:", a + b)

    def sub(self):
        a = 20
        b = 30
        print("Result:", a - b)


print("------------------------------")
x = Math()
y = Math()
z = Math()
x.add()
y.sub()
print("------------------------------")
