For every finite Abelian group Γ and for all , if there exists a solution of the equation in non-negative integers , where are positive integers, then the number of such solutions is estimated from below in the best possible way.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm6145-12-2015, author = {Maciej Zakarczemny}, title = {Number of solutions in a box of a linear equation in an Abelian group}, journal = {Colloquium Mathematicae}, volume = {144}, year = {2016}, pages = {17-22}, zbl = {06545374}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm6145-12-2015} }
Maciej Zakarczemny. Number of solutions in a box of a linear equation in an Abelian group. Colloquium Mathematicae, Tome 144 (2016) pp. 17-22. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm6145-12-2015/