Answer :
[tex]C(x) = 80,000 + 10x\ \ \ \wedge\ \ \ R(x) = 18x\\\\R < C\ \ \ \Leftrightarrow\ \ \ \ 18x<80,000+10x\\ \\8x<80,000\ /:8\\ \\x<10,000\\ \\Ans.\ The\ company\ loses\ money\ at\ level\ of\ production\ 10,000\ radios.[/tex]