If we label the bits B3, B2, B1, B0 it should be manifestly clear that there are six values greater than 9, namely 10, 11, 12, 13, 14, and 15
Each of them has B3 = 1. Equally clearly the value of B0 is a don't care -- that is it has no effect on the result. What we are left with is that either B2 or B1 or both must be equal to 1.