1. les dice (the seller would tell, not ask, the price; clientes is plural so you use les)
2. le escribe (you're writing to your mother in order to know if she wants a new purse)
3. te dan (it means do your friends give you many gifts on your birthday)
4. le vende (she's selling it to Cristina; she's only selling one)
5. le describen (they're describing the new mall; mall is the direct object so it's singular)
6.le paga (you pay with a credit card, not lend, and it's 'le' because it's usted)
hope I helped!
