(7.4x-12.3x)-(1.56-2.3x)=2.6x

7.4x-12.3x-1.56+2.3x=2.6x

7.4x-12.3x+2.3x-2.6x=1.56

-5.2х=1.56

х=1.56/-5.2

х=-0.3