A pack of 12 cans 12-oz Pepsi is priced at $3.5 at WalMart, and it can sell 100,000 units in a normal week. Two weeks ago, the store manager lowered the price to $2.99 and saw volume sales increased to 120,500 units. The manager was happy with the results and further supported the price cut with some in-store merchandising last week, and the volume sales increased to 143,900 units. Calculate the two effects separately -- price effect and promotion effect.

(1) the impact on volume (in units) of the price cuts only;

(2) the impact on volume (in units) of the in-store merchandising only