Please help with this!!!

3/8-9/4[(-5/4)+(-1/10)]

I cannot figure this out.

3/8-9/4[(-5/4)+(-1/10)]

3/8 - 9/4 [-25/20 - 2/20]
3/8 - 9/4 (-27/20)
3/8 + 243/80
30/80 + 243/80
273/80