7. Решите уравнения. а) 4 640 : x + 18 290 = 9 806 + 8 564; б) 81 · y − 267 = 13 299 − 7 896.

а) \(4\,640 : x + 18\,290 = 9\,806 + 8\,564\)

\(4\,640 : x + 18\,290 = 18\,370\)

\(4\,640 : x = 18\,370 - 18\,290 = 80\)

\(x = 4\,640 : 80 = 58\)

б) \(81 \cdot y - 267 = 13\,299 - 7\,896\)

\(81 \cdot y - 267 = 5\,403\)

\(81 \cdot y = 5\,403 + 267 = 5\,670\)

\(y = 5\,670 : 81 = 70\)

Ответ: а) \(x = 58\); б) \(y = 70\).