You have 64 grams of a radioactive kind of europium. How much will be left after 39 years if its half-life is 13 years?

c

step-by-step explanation:

below

step-by-step explanation:

1. 5/1

2. 10/16

3. 90/2

4. 1/20

5. 3/1

6. 14/24

7. 1/4

8. 18/10

x=-2

step-by-step explanation:

i began by flipping the problem to give me x= on the left (keeps it clearer for me).   so my problem simply became 10x-3=4x-6.  

1)   subtract 4x from the right side, which equals 0.   you do the same to the left of the equal as the right; therefore, subtract 4x from 10x, leaving 6x on the left.

              10x-3=4x-6   :   4x-4x on the right leaves only the -6        

2)             6x-3= 0-6 :    

                6x+3=   -6

3) divide