В) (х-5):0,7 = (2х-9):0,4;г) х:(3,8-х) = х:(5,6-3х).P.S. Заранее спасибо!

В)
$\frac{x-5}{0,7}= \frac{2x-9}{0.4} \\ (x-5)0.4=(2x-9)0.7 \\ 0.4x-2=1.4x-6.3 \\ 0.4x-1.4x=2-6.3 \\ -x=-4.3 \\ x=4.3$

г)
$\frac{x}{3.8-x}= \frac{x}{5.6-3x} \\ 3.8-x \neq 0; 5.6-3x \neq 0 \\ x(5.6-3x)=x(3.8-x) \\ 5.6x- 3 x^{2} =3.8x- x^{2} \\ -3 x^{2} + x^{2} -3.8x+5.6x=0 \\ -2 x^{2} +1.8x=0 \\ 2 x^{2} -1.8x=0 \\ x(2x-1.8)=0 \\ x_{1}=0 \\ x_{2} =0.9$