Question

Решите уравнение:
1,7х+3,1х+21=57

Answer 1

1.7х + 3.1х = 57 - 21

4.8х=36

х=36 :4.8 

х=7.5

Answer 2

$1,7x+3,1x+21=57\\ 4,8x+21=57\\ 4,8x=57-21\\ 4,8x=36\;\;|:4,8\\ \boxed{x=7,5}$