Answer:
You can complete the mission 5 times before you earn less than 400 points.
Explanation:
[tex]100(0.8)^n^-^1 < 400[/tex]
[tex](0.8)^n^-^1 < 0.4[/tex]
[tex]log 0.8^n < log 0.32[/tex]
[tex]n > 5.1[/tex]
