Amanufacturer makes a claim about its product in a tv commercial which is the best way to tell weather the claim is genuine

If I wanted to know if the product is good, then I would speak to a consumer who has used the product.

This is a pretty on point question because all we need to do is replace 's' in the equation with '35'.the calculation will be9.95 + 0.30s = c9.95 + 0.30 (35) = c9.95 + 10.5  = cc = 20.45