let's start by getting both squares as the same number
[tex]3 \sqrt{54} = 3 \sqrt{9 \times 6} = 3 \times 3 \sqrt{6} = 9 \sqrt{6} [/tex]
and
[tex]4 \sqrt{24} = 4 \sqrt{4 \times 6} = 2 \times 4 \sqrt{6} = 8 \sqrt{6} [/tex]
now we can subtract!
[tex]9 \sqrt{6} - 8 \sqrt{6} = \sqrt{6} [/tex]
so our answer is B
