I want to write down to 1 decimal place in C language.

#include<stdio.h>
int main(void){
  double a, b, c, Sum, Ave;
  printf("Input your scores:\n";
  printf("Math:");
  scanf("%lf", & a);
  printf("English:");
  scanf("%lf", &b);
  printf("Science:");
  scanf("%lf", &c);

  Sum = a + b + c;
  Ave = Sum/3;
  if(Sum<=179)
    printf("Your grade is F, Average is%.lf.\n", Ave);
  if(Sum>=180&Sum<=209)
    printf("Your grade is C, Average is %.lf.\n", Ave);
  if(Sum>=210&Sum<=239)
    printf("Your grade is B, Average is %.lf.\n", Ave);
  if(Sum>=240&Sum<=269)
    printf("Your grade is A, Average is %.lf.\n", Ave);
  if(Sum>=270)
    printf("Your grade is A++, Average is%.lf.\n", Ave);
  return 0;
}