Answer: 
Step-by-step explanation:
We know that the general form of the exponential decay formula is
, where y is final amount remaining after t time, A is the original amount and r is the rate of decay
Now, the ratio of strontium-90 remaining, p , as a function of years, t , since the nuclear accident. 
Hence, the ratio of remaining since the nuclear accident is 
Answer:
4
Step-by-step explanation:
7 is a Prime number and has 4 integer divisors
These are ± 1 and ± 7
Sweater: 1/3 = 0,333
Jeans: 3/5 = 0,6
1 – 0,6 – 0,333 = 0,067
So the 36$ represents 6,7% of all the money he had at first. (just for you to know 1 represents 100% of the money he had)
Now, you just have to use the rule of three
0,067 = 36
0,333 = x
(0,333•36)/0,067= 179,1$
The sweater costed 179,1$
4 quarters 3 dimes
4 times .25 equals $1.00
3 times .10 equals .30
1.00 plus .30 equals 1.30