Right now, the woman’s weight is in Newtons. Weight is always measured in Newtons (N), and mass will always be measured in kilograms (kg), so we need to convert her weight in Newtons into mass in kilograms. The equation for weight is Fg = mg. Force of gravity equals mass times gravity.
Force of gravity is another way of saying weight. We are given her weight, and we also know that gravity is 9.8m/s^2; therefore, you can set up your algebraic equation like this: 857 = m x 9.8. Now, you have to divide 857 by 9.8 to get mass by itself. 857/9.8 is approximately 87.4489 kilograms.
So your answer is 87.4489 kg!
The full answer is 87.44897959, but in physics, we usually just like to use the four numbers after the decimal place.