Find the transfer function from the system of equations

For example, I have a system of equations, e.g.

begin {cases}
a_1 x + b_1 y + c_1 z = d_1, \
a_2 x + b_2 y + c_2 z = d_2, \
a_3 x + b_3 y + c_3 z = d_3,
end {cases}

and for that I have to find $ x / y $ in the edition. These are just example equations. The real equations may be bigger with more variables, but I need one $ x / y $ (Transfer function in the output).