Question $3$

You combine two thin lenses by placing them in contact so that their axes coincide, forming what is called a compound lens. The focal lengths of the lenses are $30$ cm and $-50$ cm $,$ respectively. If an object is $15$ cm tall and $\backslash (\backslash$mathrm$\{$d$\}1=8\backslash$mathrm$\{$~cm$\}\backslash ),$ what is the height of the image $($unit in centimeters, cm$)?$ Express the answer as a positive quantity.