Concept:
The total moment of inertia is the sum of the moments of inertia of the individual spheres. Since the axis does not pass through the centers (it is tangential), we use the Parallel Axis Theorem: \(I = I_{cm} + md^2\), where \(I_{cm} = \frac{2}{5}mR^2\) for a solid sphere and \(d=R\).
Step 1: Calculate \(I_1\).
\(m_1 = 10\), \(R_1 = 0.2\) m.
\[ I_1 = \frac{2}{5}m_1 R_1^2 + m_1 R_1^2 = \frac{7}{5}m_1 R_1^2 \]
\[ I_1 = 1.4 \times 10 \times (0.2)^2 = 14 \times 0.04 = 0.56\,\text{kg m}^2 \]
Step 2: Calculate \(I_2\).
\(m_2 = 5\), \(R_2 = 0.1\) m.
\[ I_2 = \frac{7}{5}m_2 R_2^2 \]
\[ I_2 = 1.4 \times 5 \times (0.1)^2 = 7 \times 0.01 = 0.07\,\text{kg m}^2 \]
Step 3: Total Moment of Inertia.
\[ I_{total} = I_1 + I_2 = 0.56 + 0.07 = 0.63\,\text{kg m}^2 \]
\[
\boxed{I = 0.63\,\text{kg m}^2}
\]