double m1;
double m2;
Scanner scanner = new Scanner(System.in);
System.out.print("小明的第一次成绩:");
m1 = scanner.nextDouble();
System.out.print("小明的第二次成绩:");
m2 = scanner.nextDouble();
double left = m2-m1;
double res = (left / m1) * 100;
System.out.printf("小明的成绩提高了%.2f%%",res);