# Subgroups of $SL(n,F)$ that contain $B \cap SL(n,F)$

The exercise is from the book by Alperin 'Groups and Representations' If $$B$$ is the usual Borel subgroup of $$GL(n,F)$$. Determine all the the subgroups of $$SL(n,F)$$ which contain $$B\cap SL(n,F)$$.

So $$B$$- consists of all invertible upper triangular matrices. $$SL(n,F)$$- special linear subgroup that consist of all marices with determinant equal to 1. Hence $$B\cap SL(n,F)$$ is the set of all triangular invertible matrices with determinant equal to 1.

How do I determine subgroups of $$SL(n,F)$$ which contain that kind of matrices?