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:
16.9
Step-by-step explanation:
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40% of 39.99=15.95
6% of 15.95= 0.95
15.95 × 0.95=16.9
You would divide negative 3 (-3) from both sides to keep the c by itself. When you divide a positive by a negative it becomes negative.
Dividing 15 by -3 would equal -5, so c = -5