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 
It starts becoming bigger :)
A(-7,-4) B(-2,0)
√[(x'-x)^2+(y'-y)^2]
√(-2-(-7)^2+(0-(-4)^2
√(5^2)+(4^2)
√25+16
√41
the distance is approximately 6.4 units
-4,6) (8,-12)
square root of 12^2+-18^2
<span>square root of 144+324
</span><span>square root of 468
21.63
</span>
-15u+30
Have a great day! :)