№10

21y-5*(2y-7)=19

21y-10y+35=19

11y=19-35

y=-16/11 =- 1 ц 5/11

№11

7x+21,1=  5-x  

     12         0,6

(7x+21,1)*0,6 =(5-х)*12

4,2х+12,66=60-12х

4,2х+12х=60-12,66

16,2х=47,34

х=47 ц 34 /100: 16 ц 2/10

х=4734     *  10__  =263 /90= 2ц 83/90

      100         162

Verified answer

21y-5(2y-7)=19

21y-10y+35-19=0

11y+16=0

y=-16/11 (~-1.45)

(7x+21,1)/12=(5-x)/0,6
7/12x+211/120-25/3+x/0.6=0

7/12x-6.575+x/0.6=0

2.25x-6.575=0

x=6.575/2.25
x=263/90 (~2.922)