The mass of an isotope decreases at a rate that is proportional to the mass at that time. The mass of the isotope was 40 grams initially, and it was 10 grams after 16 days.
What was the mass of the isotope after 20 days?

168

step-by-step explanation:

i am pretty sure that the answer is 168

it is contrapositive

i could not see the question too well so check yourself again too . this is because i want you to get it correct.

d 25 pi/6

step-by-step explanation:

the diameter is 10 inches

the radius is 1/2 of the diameter or 5 inches

the area of the circle is

a = pi r^2

  = pi 5^2

  = 25 pi

the slice is 60 degrees of the entire circle.

60 degrees out of 360   60/360 = 1/6

the area of the slice is 1/6 of the circle

a slice = 1/6 a circle

a slice = 1/6 * 25 pi