678+1357=2035
а)2035-1357=678
б)2035-678=1357
(X+3)*5= 725
5x+ 15=725
5x= 725-15
5x= 710
X=142
1)(156-105)*8=51*8=408
2)540:90+320=6+320=326
500000+60000+900+1
1000000+500000+80000+300+60+4
8000000+500000+60000+1000+400+50+2
Х=0,12444...
1000х= 124,44...
100х=12,444...
1000х-100х= 124,44... - 12,44...
900х= 112.
х= 112/900
х= 28/225.
Ответ: 28/225.