solve for y: xy-3x=30 I so far have xy=33 ?

This isn't very hard actually lets look at the problem:

xy-3x=30

well lets divide add 3x to both sides:

we are left with xy=30+3x

now lets divide both sides by x
we are left with y=30+3 because the x's cancel out

so now we are left with y=30+3
so you=33

xy - 3x = 30
xy = 3x + 30
y = (3x + 30)/x
y = 3x/x + 30/x
y = 3 + 30/x

xy-3x=30
x(y-3) = 30
(y-3) = 30/x this is a rectangular Hyperbola

y = 30/x + 3 the hyperbolic has asymptotes x=0 and y= 3

note
(x-a) & (y-b) move{translate} the origin to (a,b)

xy-3x=30 add 3x to both sides
xy = 30+3x then divide both sides by x
y = (30+3x)/x
y = 3(10+x)/x

y=(30+3x)/x

y = (30+3x)/x

xy - 3x = 30

y -3 = 30/x

y = 30/x -3

y=(30+3x)/x