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Firstly for Io orbiting Jupiter, applying NII for circular motion:$$\frac{GM_{J}M_{I}}{r_{I}^{2}}=M_{I}r_{I}\omega ^{2}$$$$M_{J} = \frac{4\pi^{2}r_{I}^3}{GT^{2}}=1.9\times10^{27} kg$$Now for the Earth, using the definition of gravitational field strength:$$g=\frac{GM_{E}}{r_{E}^{2}}\implies M_{E} = \frac{gr_{E}^{2}}{G}=6.0 \times 10^{24} kg$$Finally for a general body of mass m orbiting the sun in circular motion of radius r:$$\frac{GM_{S}m}{r^{2}}=mr\omega^{2}=\frac{4\pi^{2}mr}{T^{2}}$$$$C = \frac{T^{2}}{r^{3}} = \frac{4\pi^{2}}{GM_{S}} \implies M_{S} = \frac{4\pi^{2}}{GC} = 2.0 \times 10^{30} kg$$