Answer
$$1.5 \times 10^{10} \mathrm{y}
$$
Work Step by Step
The time to lose $0.10 \%$ of its total mass is
$$
t=\frac{0.0010 M}{d M / d t}=\frac{|0.0010|\ | 2.0 \times 10^{30} \mathrm{kg} |}{\left|4.3 \times 10^{9} \mathrm{kg} / s\right|\left|3.15 \times 10^{7} \mathrm{s} / \mathrm{y}\right|}=1.5 \times 10^{10} \mathrm{y}
$$
