first distribute
a(b+c)=ab+ac
y(x+z)=yx+yz
3z(x+y)=3zx+3zy
so now we have
yx+yz=3zx+3zy
make all x's on one side
subtract 3zy frm btohs ides
yx-3zx+yz=3zy
subtract yz frmo both sides
yx-3zx=3zy-yz
undistribute the x on the left side
x(y-3z)=2zy
divide both sides by (y-3z)
x=\(\frac{2zy}{y-3z}\)
