(3891-х)+25419=27090
(3891-х) = 27090 - 25419
3891-х = 1671
х = 3891 - 1671
х=2220
проверка (3891 - 2220) + 25419 = 27090
1671+ 25419=27090
27090 = 27090
100001-(х+44864)=31587
х+44864=31587 + 100001
х+44864=131588
х=131588-44864
х=86724
проверка
100001-(86724+44864)=31587
100001-131588=31587
31587=31587