You cannot add something to a non-existent value; The first call would be:
$total += (float)$roi;
This is not possible, so Add/Initialize the variable$total = 0;
before your $the_query loop.
You cannot add something to a non-existent value; The first call would be:
$total += (float)$roi;
This is not possible, so Add/Initialize the variable$total = 0;
before your $the_query loop.