Symbiosis National Aptitude Test SNAP 2016 Paper

As 43 is neither a multiple of 5 nor 6, either statement alone is not sufficient to answer the question.
Using both statements together: Let the number of children older than 5 years be 'a' and that of 5 years or younger be 'b'.
As per the given information, 5a + 6b = 43.
As a and b are non-negative integer, only possible value: a = 5 and b = 3.