=CONCATENATE(TEXT(SUM(A1,A

I also question whether you should be multiplying B2/B5 by 100 if you want the result to be displayed as %. You probably meant to write it like:

=CONCATENATE(TEXT(SUM(A1,A

Note that I omitted the SUM in the second TEXT because there was only one value being converted. If the / was a typo and you meant to sum, then the formula would be:

=CONCATENATE(TEXT(SUM(A1,A