Alright, so I've got sin(5/13) and I've tan(-sqrt3)

Find tan (alpha-beta), please help!!! for exact value

I'm instructed to use tan(a+b)=tanx-tany/1+tanx(tany), and utilising properties of triangles I can resolve that sin(5/13) has a tan of (5/12)

/I plug it in to my equation to get [(5/13)+(-sqrt3)]/[1+(5/12)(-sqrt3)].. man I'm lost