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