[tex]\beta=\frac{y_2}{y_1}=\frac{-40}{10}=-4\\ \beta=-\frac{x_2}{x_1}=>x_2=-\beta x_1=4*(-60)=-240 cm=>x_2=-240 cm\\\frac{1}{x_2}+ \frac{1}{x_1}=\frac{1}{R}<=>\frac{1}{-240}+ \frac{1}{-60}=\frac{1}{R} =>\frac{1}{R}=-\frac{5}{240}=-\frac{1}{48}=>|R|=48 cm\\[/tex]
