Solution

Let 

$G$ be random variable for gain ( in thousand dollars ) of insurance company.

Let $z$ be the premium ( in thousand dollars ) that should be charged to break even.

Given:

$$p(G=z-800)=0.01, ~~~ p(G=z-250)= 0.05$$

$$p(G=z)= 1- 0.01-0.05=0.94$$

Answer

$ 20500