The chemical element einsteinium-

naturally loses its mass over time. A sample of einsteinium-

had an initial mass of

grams when we measured it.
The relationship between the elapsed time

, in days, and the mass,

, in grams, left in the sample is modeled by the following function:


Complete the following sentence about the rate of change in the mass of the sample.
The sample loses

of its mass every
days.