Х+21=7
Х=7-21
Х=-14
32+х=-25
Х=-25-32
Х=-57
Х+12,5=-7,5
Х=-7,5-12,5
Х=-20
15,2+х=2,3
Х=2,3-15,2
Х=-13,1
Х-8,9=-5
Х=-5+8,9
Х=3,9
12,5-х =-10
Х=12,5-(-10)
Х=22,5
-7х+13х+9=-19+13х
-7х+13х-13х=-19-9
-7х= -28
х= (-28): (-7)
х= 4
Проверим:
-7*4+13*4+9 = -19+13*4
-28+52+9= -19+52
61-28 = 52-19
33=33
1) 475-76.4=398.6
2) 398.6:13.2= 30.19
3)9.75+30.19=39.94
Б = 2*4 = 8
БББ = 888
888/4 = 222
222 * 4 = 888