Kenneth S. answered 04/13/18
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Expert Help in Algebra/Trig/(Pre)calculus to Guarantee Success in 2018
n - 6 = 2n + 1 ⇐that's what the words in your title say.
So, solve for n. Your gratuitous "it has to be in negative numbers" is not necessary; it will be whatever it has to be, as determined by regular algebra rules.