重复的步骤可以合并，特殊字符输出要在前面加转义字符\，%输出用%%

#include<cstdio>
int main()
{
    double a,x;
    scanf("%lf",&a);
    if(a<=400) x=0.15;
    else if(a<=800) x=0.12;
    else if(a<=1200) x=0.1;
    else if(a<=2000) x=0.07;
    else x=0.04;
    printf("Novo salario: %.2lf\n",a*(1+x));
    printf("Reajuste ganho: %.2lf\n",a*x);
    printf("Em percentual: %.0lf %%\n",x*100);
    return 0;
}