Answer:
It's 7!
Step-by-step explanation:
6 = -2b (cancel -2b on both sides)
6/-2 = b (divide both sides by -2)
-3 = b (simplify 6/2 to 3)
now switch sides
Answer: b = -3
1. 12=x+3 12-3=9 now try 9+3 that is 12 so x=9
2. b+0.6=-1 -1-0.6=-1.6 -1.6+0.6=-1 b=-1.6
3. a=-9
4. x=-39 I believe
5. a=-4.3
I dont know man you gotta ask a question

2) 5.625 mg will be left
Explanation:
1) Half-life = 17.5 days
initial amount of Arsenic-74 = 90 mg
To get the equation, we will use the equation of half-life:


2) we need to find the remaining amount of Arsenic-74 after 70 days
t = 70

So after 70 days, 5.625 mg will be left