Question

Решите уравнения 20 2(х-8)=20 -5(3х-6)=30 3(2,1х-4)=4,2 7а=0,07 15а=1 0,5х- 1,2=3,8

Answer 1

1) 2(x-8) =20;
x - 8 = 10  ;    
x=10+8;
x=18.
2) - 5 (3x -6) =30 ;
-5*3(x-2)  =30 ;
x-2 =  - 2;
x=0

3)
 3(2,1x- 4) =4,2 ;
2,1x -4 =1,4;
2,1x =4+1,4;
2,1x =5,4 ;
x = 18/7.
4) 7a = 0,07;
a = 0,07 : 7 ;
a =0,01.
5)
15a = 1;
a = 1/15. 
6)
0,5x - 1,2 =3,8  ;
0,5x =3,8+1,2 ;
0,5x = 5 ;
x= 5 :0,5;
x=10.

Answer 2

1) 2(x-8) =20; x - 8 = 10 ; x=10+8; x=18. 2) - 5 (3x -6) =30 ; -5*3(x-2) =30 ; x-2 = - 2; x=0 3) 3(2,1x- 4) =4,2 ; 2,1x -4 =1,4; 2,1x =4+1,4; 2,1x =5,4 ; x = 18/7. 4) 7a = 0,07; a = 0,07 : 7 ; a =0,01. 5) 15a = 1; a = 1/15. 6) 0,5x - 1,2 =3,8 ; 0,5x =3,8+1,2 ; 0,5x = 5 ; x= 5 :0,5; x=10.