Answer:
The plans will cost the same when the amount you have to pay for talking for "x" minutes on Plan A is the same has what you have to pay for talking for the same number of "x" minutes when using Plan B.
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$ Plan A = $ Plan B
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To find the charge on each plan we add the base rate to the per minute call rate for each.
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Plan A = $27 + $0.11x
Plan B = $13 + $0.15x
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Let's drop the $ sign for now and get rid of the decimal point by multiplying by 100.
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2700 + 11x = 1300 + 15x
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Subtracting 11x and 1300 from both sides:
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4x = 1400
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x = 350 min.
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Using this result the plans both cost $65.50 for 350 min of talk time.
Step-by-step explanation:
boom  :)