Ответ:

а) \(12\,480+9\,520=22\,000\), \(22\,000-8\,000=14\,000\).

б) \(70\,000-18\,765=51\,235\), \(51\,235+2\,100=53\,335\).

в) \(34\,900+1\,100=36\,000\), \(36\,000-7\,250=28\,750\).

Ответ: а) 14 000; б) 53 335; в) 28 750.