Answer:
I think its A, Because if you look at the problome A makes sense

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
You must first simplify the radicals by taking out any perfect squares.
√8 + 3√2 + √32 =
√4 * √2 + 3√2 + √16 * √2 =
2√2 + 3√2 + 4√2 =
9√2