Sum of all previous colmns

Good day all,

please assist with the below:

I have a report like the above, I want to, for example to find the total of all stores, i.e (8+10+14+4+2 =38), then use column #SALONS AUDITED to calculate the last total, e.g. %AUDITED dean : 4/38= 10.53%; lani : 5/38 = 13.16%; vette : 7/38 = 18.42%, etc

Regards

Zimiso