The answer would be h+(h+2.5)=22
The h represents Williams hours and the h+22 represents jose's hours. Together, they add to 22 hours :)
Hope this helps!
B. (2,20] is the correct answer
Answer:

Step-by-step explanation:
What are you supposed to be doing
Answer:
8978 grams
Step-by-step explanation:
The equation to find the half-life is:

N(t) = amount after the time <em>t</em>
= initial amount of substance
t = time
It is known that after a half-life there will be twice less of a substance than what it intially was. So, we can get a simplified equation that looks like this, in terms of half-lives.
or more simply 
= time of the half-life
We know that
= 35,912, t = 14,680, and
=7,340
Plug these into the equation:

Using a calculator we get:
N(t) = 8978
Therefore, after 14,680 years 8,978 grams of thorium will be left.
Hope this helps!! Ask questions if you need!!