Ascientist has a 120 mg sample of an unstable isotope. the amount of the substance remaining in the sample decreases at a rate of 16% each day. at the end of t days, there is less than 30 mg of the substance remaining. which inequality represents this situation, and after how many days will the sample size remaining be less than 30 mg?

Which statement explains how you could use coordinate geometry to prove the opposite sides of a quadrilateral are congruent? a. use the slope formula to prove the slopes of the opposite sides are the same. b. use the slope formula to prove the slopes of the opposite sides are opposite reciprocals. c. use the distance formula to prove the lengths of the opposite sides are the same. d. use the distance formula to prove the midpoints of the opposite sides are the same.