Question

Make x the subject of y(x+z)=3z(x+y)

Answer 1

y(x+z) + 3z(x+y)

yx + yz + 3xz + 3yz

yx =3xz +4yz

yx - 3xz = 4yz

Divide both sides by yz

x - 3x = 4yz / yz

-2x = 4

Answer 2

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=$\frac{2zy}{y-3z}$