Final answer:
The number of additional minutes that result in the same monthly cost for both companies is 100 minutes. The calculation is done by equating the total cost equations of the two companies and solving for x, which represents the additional minutes used.
Step-by-step explanation:
To calculate how many additional minutes result in the same monthly cost between two different phone company plans, we need to set up an equation for each company and then equate them. Company A charges a monthly fee of $60 plus 50 cents for each additional minute of use. Company B charges $50 per month plus 60 cents for each additional minute. Let x represent the number of additional minutes used per month.
The cost for Company A would be: Cost A = 60 + 0.50x
The cost for Company B would be: Cost B = 50 + 0.60x
To find where the cost would be the same, we equate the two costs:
60 + 0.50x = 50 + 0.60x
Subtracting 0.50x from both sides, we get:
60 = 50 + 0.10x
Now subtract 50 from both sides:
10 = 0.10x
Finally, divide both sides by 0.10 to find x:
x = 100
So, the number of additional minutes that would result in the same monthly cost for both companies is 100 minutes, which corresponds to answer D.