string kampania(NapBon x1, NapBon y1, NapBon x2, NapBon y2){

a = (x2 - y2) / (x1 - y1);                 //
b = ((x1 * y2) - (x2 * y1)) / (x1 - y1);   // bledne

NapBon a;
NapBon b;

a.x = (x2.x - y2.x) / (x1.x - y1.x);
b.x = ((x1.x * y2.x) - (x2.x * y1.x)) / (x1.x - y1.x);

double tmp = a * 100.0 + 0.5;            //
a = floor(tmp) / 100.0;                  // bledne

NapBon tmp;
tmp.x = a.x * 100.0 + 0.5;
a.x = floor(tmp.x) / 100.0;