A store has five shelves and the average weekly sale of the store is tk. 30,000. Shelf 1 accounted for 1/4 of the store's average weekly sales and stores 2 and 3, each accounted for 2/3 as much as shelf 1. If shelf 4 alone accounted for as much as shelf 1 then, which of the following could have been the average weekly sales of shelf 5 for the store?