391500=870*450-261*1500-(879457-487957)= (63512-59996)*27*3-3516*3= 189372-(96255+400821): 69-39440: 8=

391500+870*450-261*1500-(879457-487957)=0
1) 870*450=391500
2)251*1500=391500
3) 879457-487957=391500
4)391500+391500=783000
5)783000-391500=391500
6)391500-391500=0

(63512-59996)*27*3-3516*3=263700
1) 63512-59996 = 3516
2) 3516*3 = 10548
3) 3516*27 = 94932
4) 94932*3 = 284796
5) 284796 - 10548 = 263700  

189372+(96255+400821):69-39440:8=191646
1) 96255+400821=497076
2) 497076:69=7204
3) 39440:8=4930
4) 189372+7204=196576
5) 196576-4930=191646