This is how it would look like, hope that this is not too late to help you yet!
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13x + 13 + 2x = 2
15x + 13 = 2
15x = -11
Answer:

Step-by-step explanation:
The half life is the amount of time it takes a substance to decay to half of its original amount.
Since the radioactive substance has a half life of 1000 years, there will be half of it left after 1000 years.
So, the fraction that will be left after 1000 years is 
52.7 ÷ 4.25 = 12.4
Hope that helps ....