The population Pa of insect A after t years is given by the equation
Pa = 1.3(1-0.038)^t
while the population Pb of insect B after t years is
Pb = 2.1(1-0.046)^t
We equate the above expressions to find the number of years t it will take the two populations to be equal:
Pa = Pb
1.3(1-0.038)^t = 2.1(1-0.046)^t
1.3(0.962)^t = 2.1(0.954)^t
These are the equations that can be used to determine how long it will be before the populations of the two species are equal.
We can now solve for t:
(0.962)^t / (0.954)^t = 2.1/1.3
(0.962/0.954)^t = 2.1/1.3
After taking the log of both sides of our equation, number of years t is
t = log (2.1/1.3) / log (0.962/0.954)
t = 57 years
Therefore, it will take 57 years for the population of insect A to equal the population of insect B.
The balanced equation for the given reaction 
<h3>What is a double replacement reaction?</h3>
A double replacement is a chemical reaction that takes place in which two reactants swap cations or anions to produce two distinct products.
Whenever the cations representing one of the reactants interact with the anions from another reactant to produce an insoluble ionic compound, a precipitate occurs.
The balanced equation for the given reaction:

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Answer:
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Step-by-step explanation:
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I hope I helped you^_^
Answer:
the first term is a1
the distance between the numbers is d
we have:
a5 = a1 + 4d = 23
a12 = a1 + 11d = 72
so we have the equation:
a1 + 4d = 23
a1 + 11d = 72
=> a1 = -5
d = 7
=> an = -5 + 7(n - 1) = 7n - 12
with an = 7n - 12
=> a2 = 2
a3 = 9
so the first three terms is -5; 2; 9