Both are different. Sales Volume: Is the amount of sales (i.e. In USD), it is the value of the all products have been sold in a certain period of time (day, month, year,..) Market Share: Is the percentage that a certain product has among the other competitors for the same product category.  Hope my answer … Read more

Multiply the number you want to deduct 20% into 0.8 for example if you want to deduct 20% from 100 = 100 * 0.8 = 80