Question

-12+(x-5.3)=0.9 

0.3-(7.2=3)=0.9

 

Answer 1

-12+(x-5.3)=0.9 
-12 +x-5,3=0,9
x=0,9+12+5,3
x=18,2
0.3-(7.2-x)=0.9 
0,3 -7,2+x=0,9
x=0,9+7,2-0,3
x=7,8

Answer 2

-12+(x-5.3)=0.9
x- 5.3=12.9
x= 12.9+5.3
x= 18.2

 0.3-(7.2=3)=0.9
а тут без переменных?