extension Int { var add: Int {return self + 100 } var sub: Int { return self - 10 } var mul: Int { return self * 10 } var div: Int { return self / 5 } } let addition = 3.add print("加法运算后的值：\(addition)") let subtraction = 120.sub print("减法运算后的值：\(subtraction)") let multiplication = 39.mul print("乘法运算后的值：\(multiplication)") let division = 55.div print("除法运算后的值: \(division)") let mix = 30.add + 34.sub print("混合运算结果：\(mix)")