To find the difference in the total costs of the two cell phone plans when a customer talks for 20 minutes, we need to determine the total cost for both Plan A and Plan B at 20 minutes.
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Calculate the cost for Plan A: From the table provided for Plan A, we can observe the pattern based on the given costs for the minutes used. It looks like the cost increases by $0.10 for every 2 minutes.
- When “m = 0”, cost = $35.00
- When “m = 2”, cost = $35.10
- When “m = 4”, cost = $35.20
It's evident that for every 2 minutes, the cost increases by $0.10, which translates to an increase of $0.05 per minute.
Thus, we can write a rule: \[ \text{Cost for Plan A} = 35 + (0.05 \times m) \]
For 20 minutes: \[ \text{Cost for Plan A} = 35 + (0.05 \times 20) = 35 + 1.00 = 36.00 \]
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Calculate the cost for Plan B: The relationship for Plan B is given by the equation: \[ c = 30 + 0.10m \]
For 20 minutes: \[ c = 30 + (0.10 \times 20) = 30 + 2.00 = 32.00 \]
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Calculate the difference in costs: Now we find the difference between the costs of Plan A and Plan B. \[ \text{Difference} = \text{Cost of Plan A} - \text{Cost of Plan B} = 36.00 - 32.00 = 4.00 \]
Therefore, the difference in the total costs of the cell phone plans if a customer talks for 20 minutes is $4.00.
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