Error message in shopping cart please help!!!!

Hello everyone

Everytime I add something in the shopping cart and i click to view it or check out, it gives me the following message:

Sub-Total:
Notice:
Undefined variable: subtotal in
/home/content/p/a/g/pagepeekadk/html/SSJ/catalog/view/theme/EUOC00001/template/module/cart.tpl
on line 21

Please help me or tell me what the error is for and how can I fix this.

Thank you

If this is not the default template I suggest you contact the seller/builder of it.