Answer to 1: 648
Answer to 2: 175
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 
Slope = 4 but I need to get to 20 characters to reply to this question. Have a nice day
Wait, this is simplified because there are no common terms.
Answer:
5 or 6
Step-by-step explanation: