a)
[tex]x=4\\\\3x-2=3\cdot4-2=12-2=\boxed{10}[/tex]
b)
[tex]x=-3\\\\7-9x=7-9\cdot(-3)=7+27=\boxed{34}[/tex]
c)
[tex]x=-2\\\\x^2+3x+1=(-2)^2+3\cdot(-2)+1=4-6+1=-2+1=\boxed{-1}[/tex]
d)
[tex]x=4,2\\\\\frac{3-2x}{3+x}=\frac{3-2\cdot4,2}{3+4,2}=\frac{3-8,4}{7,2}=\frac{-5,4}{7,2}=-\frac{54}{72}=-\frac{3}{4}=-\frac{75}{100}=\boxed{-0,75}[/tex]
