[tex]F = G\cdot\frac{m_1\cdot m_2}{r^{2}} = 36 \ N\\\\a) \ F_{a} = G\cdot\frac{m_1\cdot m_2}{(4r)^{2}} =G\cdot\frac{m_1\cdot m_2}{16r^{2}} = \frac{1}{16}\cdot G\cdot\frac{m_1\cdot m_2}{r^{2}} = \frac{1}{16}F = \frac{1}{16}\cdot36 \ N = 2,25 \ N\\\\b) \ F_{b} = G\cdot\frac{10m_1\cdot m_2}{r^{2}} = 10\cdot G\cdot\frac{m_1\cdot m_2}{r^{2}} = 10F =10\cdot36 \ N = 360 \ N[/tex]