This is the most standard curriculum. Solutions are usually found for the " Рабочая тетрадь " (Workbook) by L.S. Atanasyan.
Another popular series by A.G. Merzlyak, V.B. Polonsky, and M.S. Yakir. gdz k tetradi po geometrii klass
Provides answers for various workbook editions, including newer GEF (ФГОС) versions. This is the most standard curriculum