a) [tex]-7x \geq -3x+12\\
-4x\geq 12 | :-4\\
x \leq -3 \Rightarrow x \in \lbrace...,-5,-4,-3\rbrace[/tex]
b) [tex]-3x \leq -8x\\
5x \leq 0\\
x \leq 0 \Rightarrow x \in \lbrace...-2,-1,0\rbrace[/tex]
c) [tex]3x-1 \leq -2x+4\\
5x \leq 5\\
x \leq 1 \Rightarrow x\in \lbrace ...,-1,0,1\rbrace[/tex]
d) [tex]2x-1 \geq x+5\\
x \geq 6 \Rightarrow x\in \lbrace6,7,8,...\rbrace[/tex]