Gravitational force of earth is given as weight of object
so here we know that gravitational force on Amy is 500 N
so we will have
[tex]mg = 500 N[/tex]
now we will have
[tex]g = 9.8 m/s^2[/tex]
now from above equation we will have
[tex]m (9.8 m/s^2) = 500 N[/tex]
[tex]m = \frac{500}{9.8} kg[/tex]
[tex]m = 51 kg[/tex]
so the mass of the Amy is 51 kg