The subtraction theorem states that for all real numbers,

and

,

.
(To subtract, we can add the inverse.)
Thus, we can have the these two equivalent expressions.
Step-by-step explanation:
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300 messages would have to be sent or received in order for the plan to cost same each month.
Step-by-step explanation:
Given,
Cost per month = $30
Per text sent or received charges = $0.10
Let,
x be the number of texts sent or received.
A(x) = 0.10x+30
A comparable plan costs = $60 per month
Text messages are unlimited.
B(x) = 60
For the two plans to cost equal;
A(x) = B(x)

Dividing both sides by 0.10

300 messages would have to be sent or received in order for the plan to cost same each month.
Keywords: function, addition
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Answer:
For the answer to the question above, it is -18% because to find rate we subtract the rate, in this case, is .82 or 82% - 1 or 100% and that would give you the rate, in this case, its decreasing by an 18%
-Hope this helps<3