#include<stdio.h>
 
int main()
{
    float c = 0, a = 0;
    int i = 0,b=0;
    for(i=0; i<=300; i++)
    {
        b = (int)a;
        if(b%20==0)
        {
        c = (5*( a - 32))/9;
        printf("%4.0f%10.1f\n", a, c);
        }
    a++;
    }
}

   0     -17.8
  20      -6.7
  40       4.4
  60      15.6
  80      26.7
 100      37.8
 120      48.9
 140      60.0
 160      71.1
 180      82.2
 200      93.3
 220     104.4
 240     115.6
 260     126.7
 280     137.8
 300     148.9

Exited: ExitFailure 15