#include <stdio.h>

double sum(double, double);

int main(void) {
	double a,b,c;
	a = 1.5;
	b = 2.8;
	c =sum(a,b);
	printf("%f +%f = %f\n",a,b,c);
	return 0;
}

double sum(double x, double y){
	return x+y;
}