Sites like Spishu.ru and similar "GDZ" (готовые домашние задания) portals host digital keys for workbooks. To find the correct one, search for the author's name alongside the workbook title:
Processing multimedia and formatting documents. informatika 7 klass rabochaia tetrad otvety onlain spishu.ru
Ответы информатика 7 класс Поляков (for Polyakov). Sites like Spishu
