Lisa is examining a two-way table representing the sales of juice packaged in bottles with an old or new label. in the table, p, q, r, and s are the number of bottles sold or left on the grocery store shelf last thursday.

We can use the simple rule for finding the number of sales;

Sales = number of items sold ÷ (remaining item + items sold)

Therefore,

To find out the impact of the new label on sales we can say:

Sales = number of items sold ÷ (remaining item + items sold)

Sales for new label = p ÷ (p + q)
And,
Sales for old label = r ÷ (r + s)