I'm learning how to program c and i'm trying to make a program the finds the range (using an equation with x as the domain) of a 2d grid...ive already attempted it, but it's giving me all these errors on Xcode, any help?(As you can see, I'm quite stuck!)

#include <stdio.h>
#include <stdlib.h>
float domain;

float domain = 2.0;

float domainsol(float x )
{
domain = x;
float func = 1.25 * x + 5.0;
return func;

}



int main(int argc, const char * argv[])
{

}