The answer your looking for is D
Answer: 24 grams of element would remain.
Step-by-step explanation:
Exponential function for decay:
....(i) , where A = initial value , b = decay factor, x = time , n= time per period
As per given,
A = 569 grams , 
n= 5 years, t = 23 years
Put all values in (i) , we get

Hence, after 23 years , 24 grams of element would remain.
Answer:
12-5=7 so 7 hours and we minused because we want remove h so we can minus and get the amount if hrs
Answer:
Let x = the length
Let P = the perimeter of the first pool
48 = (1/3)P
144 feet = P
P = 2l + 2w
144 = 2x + 2(24)
144 = 2x + 48
96 = 2x
48 feet = x