1)(х+3)*5=725
х+3=725:5
х+3=145
х=145-3
х=142
(142+3)*5=145*5=725
2)4949:7+х=20678
х=20678-(4949:7)
х=19971
4949:7+19971=707+19971=20678
3)2*х+908=4052
2*х=4052-908
2х=3144
х=1572
2*1572+908=3144+908=4052
4)5*b-1209=1256
5*b=1256+1209
5*b=2465
b=2465:5
b=493
5*493-1209=2465-1209=1256