a)
[tex]2x+y=7\\2x=-y+7\ |:2\\x=-\frac{1}{2}y+3\frac{1}{2}\\\\2x+y=7\\y=-2x+7[/tex]
b)
[tex]x-y=3\\x=y+3\\\\x-y=3\\-y=-x+3\ |:(-1)\\y=x-3[/tex]
c)
[tex]\frac{1}{6}y=x+2\\\frac{1}{6}y-2=x\\x=\frac{1}{6}y-2\\\\\frac{1}{6}y=x+2\ |*6\\y=6x+12[/tex]
d)
[tex]4(x-y)=3x\\4x-4y=3x\\4x-3x=4y\\x=4y\\\\4(x-y)=3x\\4x-4y=3x\\-4y=3x-4x\\-4y=-x\ |:(-4)\\y=\frac{1}{4}x[/tex]
e)
[tex]\frac{4}{5}x=\frac{2}{3}y\ |:\frac{4}{5}\\x=\frac{2}{3}y*\frac{5}{4}\\x=\frac{5}{6}y\\\\\frac{4}{5}x=\frac{2}{3}y\ |:\frac{2}{3}\\\frac{4}{5}x*\frac{3}{2}=y\\\frac{6}{5}x=y\\y=1\frac{1}{5}x[/tex]
f)
[tex]8x+4y=12\ |:4\\2x+y=3\\2x=-y+3\ |:2\\x=-\frac{1}{2}y+1\frac{1}{2}\\\\8x+4y=12\ |:4\\2x+y=3\\y=-2x+3[/tex]
