Cześć!
a)
[tex]\frac{x}{15}=\frac{4}{3}\\\\3\cdot x=15\cdot4\\\\3x=60 \ \ /:3\\\\\huge\boxed{x=20}[/tex]
b)
[tex]\frac{3-2x}{12}=\frac{3}{2}\\\\2(3-2x)=12\cdot3\\\\6-4x=36\\\\-4x=36-6\\\\-4x=30 \ \ /:(-4)\\\\\huge\boxed{x=-7,5}[/tex]
c)
[tex]\frac{6}{2-3x}=\frac{3}{7}\\\\3(2-3x)=6\cdot7\\\\6-9x=42\\\\-9x=42-6\\\\-9x=36 \ \ /:(-9)\\\\\huge\boxed{x=-4}[/tex]
d)
[tex]\frac{4}{1-x}=\frac{3}{1+x}; \ x\neq1, \ x\neq-1\\\\4(1+x)=3(1-x)\\\\4+4x=3-3x\\\\4x+3x=3-4\\\\7x=-1 \ \ /:7\\\\\huge\boxed{x=-\frac{1}{7}}[/tex]
