Formula:
\(F = G \cdot \dfrac{m_1 m_2}{r^2}\)
m1, m2 - mass in kg
r - distance in meter.
m1 = m2 = 0.1kg
r = 15m
\(F = 6.67 \cdot 10^{-11} N \cdot \dfrac{m^2}{kg^2} \cdot \dfrac{0.1 \cdot 0.1 kg^2}{15^2 m^2} \\ \\ F=\dfrac{6.67 \cdot 0.01 \cdot 10^{-11}}{225} N \\ \\ F \approx 0.00002964 \cdot 10^{-11} N \\ \\ F \approx 2.96 \cdot 10^{-16} N\)
Greetining