Solutions
Statement I:
Let the number of people who are citizens of the country and living in it be 4x
Number of people who are living in the country = 5x
Just the ratio is given, from which the number of people living in the country cannot be found out from statement I alone.
Statement II:
Number of people living in the country = 15 × Number of people who filled income tax greater than 70000 zorks
Just a relation can be found out here, hence number of people living in the country cannot be found out from statement II alone.
Using Statement I and II together:
5x = 15 × Number of people who filled income tax greater than 70000 zorks
Again, just a relation can be found out, hence number of people living in the country cannot be found out from statement I and statement II together.