negative five divided by negative three minus two times negative one third minus twenty one divided by seven

Doesn't your computer have a numbers key? It's much easier to do math that way. You will need to use parentheses to clarify the order of operation.

(-5/-3) - 2*(-1/3) - (21/7)
= (5/3) +(2/3) -3 = ?

This is not an algebra question. You are just performing basic arithmetic operations.