How do I substitute and solve? I see how it is 3.2 divide it by 1000 kg ×9.80, but I get confused with the end product.

My question is

N is Newtons

Will give for correct answer​

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.