Final answer:
Arnold would have to talk for 56.7 minutes for both phone plans to cost the same. This is found by setting the cost equation for Plan 1 equal to the flat fee of Plan 2 and solving for the number of minutes.
Step-by-step explanation:
To determine when Arnold would have the same cost under both cell phone plans, we need to set up an equation where the cost of Plan 1 equals the cost of Plan 2. For Plan 1, the cost is the monthly fee plus the per-minute charge, which is represented as $18.50 + $0.15x, where x is the number of minutes. For Plan 2, the cost is a flat monthly fee of $27. Thus, we have the equation $18.50 + $0.15x = $27.
Next, to solve for x, we subtract $18.50 from both sides of the equation:
- $18.50 + $0.15x - $18.50 = $27 - $18.50
- $0.15x = $8.50
Now, we divide both sides by $0.15 to find the number of minutes:
- x = $8.50 / $0.15
- x = 56.7 minutes
So, Arnold would have to talk for 56.7 minutes to have the same cost under both plans. The closest answer choice to this calculation is answer b) 56.7 minutes.