10 000-х =6 311
х=10000-6311
х=3689
----------------------------
10000-3689=6311
6311=6311
3 094+х = 9 001
х=9001-3094
х=5907
----------------------------
3094+5907=9001
9001=9001
х-79 = 5 483
х=5483+79
х=5562
------------------
5562-79=5483
5483=5483
х+3 210 =9 025
х=9025-3210
х=5815
------------------------
5815+3210=9025
9025=9025