[tex]f=10 cm=0,1 m\\C=\frac{1}{f}= \frac{1}{0,1}=10 \delta\\\frac{1}{x_2}- \frac{1}{x_1} =\frac{1}{f} =>x_2=\frac{fx_1}{f+x_1}=\frac{10(-5)}{10-5}=-10 cm\\\beta=\frac{x_2}{x_1}=\frac{-10}{-5}=2 \\ \beta=\frac{y_2}{y_1}=>y_2=\beta y_1=2*20=40 cm[/tex]