Can two rectangles have the same perimeter but have different a areas? how do you know.

Certainly, yes.  P is calculated thru mult. and addn., whereas A is calc. thru mult. alone.

Think of 2 rect., one 3 by 4 units.  What is the perimeter?  the area?  Suppose that the other rect. were 2 by 6 units.  What is the perim.?  the area?

Are the areas the same or diff?  Are the perimeters the same or diff?

I think this is correct but im not sure..

Step-by-step explanation:

12 days is 3 half-lives ... so, 1/8 initial ... (1/2)^3 = 1/8

... initial is 8 mg

4 weeks is 7 half-lives ... 8 mg * (1/2)^7 = ?