CONCATENATE multiple fields

I am trying to add up the values of multiple fields together so that the final output is a range (x-y).

I have used this function:

(function(){
var a = fieldname1.split('-'), b = fieldname2.split('-');
return CONCATENATE(SUM(a[0].trim(),b[0].trim()),'-',SUM(a[1].trim(),b[1].trim()));
})()

(function(){
var a = fieldname49.split('-'), b = fieldname50.split('-'), c = fieldname50.split('-'), d = fieldname50.split('-'), e = fieldname50.split('-'), f = fieldname50.split('-'), b = fieldname50.split('-');
return CONCATENATE(SUM(a[0].trim(),b[0].trim(), c[0].trim(), d[0].trim(), e[0].trim(), f[0].trim()),'-',SUM(a[1].trim(),b[1].trim(), c[0].trim(), d[0].trim(), e[0].trim(), f[0].trim()));
})()

but it’s yielding no result.

Is there anything I am missing? Please help me check.

The page I need help with: [log in to see the link]