There is no explanation for this problem, as it does not describe how the distance to the gate is related to the distance across the yard.
If we make the assumption that the cat is headed directly to the gate, which is the full distance across the yard, this question is asking you to subtract the fraction 7/16 from 1, where 1 represents the full distance across the yard. Of course, the result is (16/16 - 7/16) = 9/16 of the distance across the yard.