Customers can use a manufacturer's coupon and a store coupon to obtain a discount when buying soap powder in a certain store. In one week, 65% of customers used the store coupon when purchasing the soap powder, and 35% used the manufacturer's coupon. What percent of customers used both the manufacturer's coupon and the store coupon when purchasing the soap powder?
(1) 15% of customers used neither coupon when purchasing the soap powder
(2) 50% of customers used the store coupon but not the manufacturer's coupon when purchasing the soap powder
(1) 15% of customers used neither coupon when purchasing the soap powder
(2) 50% of customers used the store coupon but not the manufacturer's coupon when purchasing the soap powder