1) 13865 , 13867 , 13869 , 13871.
2)15934-12504 =3430
3430 + 12504 = 15934
15934- 3430 = 12504
175304-124106=51198
51198+124106= 175304
175304-51198=124106
948976-38764=910212
910212+38764 = 948976
948976-910212=38764
3)8436 = 4576+3860
8436= 4000+2500+1936
8436=10676-2240
20145= 19845+300
20145= 19845 + 167+133
20145= 39873-19728