According to Kepler's third law, mass of the sun can be calculated as follows:
[tex]T^2=\frac{4\pi^2}{GM_s}a^3\\M_s=\frac{4\pi^2}{GT^2}a^3\\M_s=\frac{4\pi^2}{6.67\times 10^{-11}(3.156\times10^7)^2}(1.496\times10^{11})^3\\M_s=1.98\times 10^{30} kg[/tex]
Kepler's third law can also be written as:
[tex]P^2=a^3[/tex]
where P is period in years and a is semi major axis in au
[tex]1au=1.496\times10^{11}m[/tex]
Substitute the values to find semi-major axis of comet's orbit around the Sun:
[tex]a^3=(296)^2\\a=44.41 au = 6.64\times10^{12} m[/tex]