Take overall minus sign in front in dot product with symbolic variables

I have the following as the output of a calculation


and I would like Mathematica to evaluate this to zero. Is there a way to specify that for my purposes (-a).b is the same as -(a.b)?

(I’ve been searching for a solution and tried a number of things but thought it would be better to keep my question clear and concise not to distract with irrelevant descriptions of my attempts solving it.)