1. Assume that the employee's monthly basic salary and the reward amount for selling each product are M yuan and N yuan respectively.

m+200n= 1800 ( 1)

m+ 180n= 1700 (2)

( 1)-(2) n=5。

Substitution into (2) gives m=800.

The basic salary is 800 yuan, and the amount of each award is 5 yuan.

2. The sales of Party C are:

(2000-800)÷5=240 pieces