A solid sphere of mass \( 5 \, \text{kg} \) and radius \( 10 \, \text{cm} \) is kept in contact with another solid sphere of mass \( 10 \, \text{kg} \) and radius \( 20 \, \text{cm} \). The moment of inertia of this pair of spheres about the tangent passing through the point of contact is ______ \( \mathrm{kg \, m^2} \).