We are going to denote the number of additional minutes with
, and the total cost of the call with
.
From PONCO, we know that they charge $1.25 for the first minute, and $0.30 for each additional minute; knowing that our additional minute is
and our total cost of the call is
, we can set up an equation to relate the values:
we are going to call this equation (1)
From CowBell, we know that they charge 1.40 for the first minute, and $0.25 for each additional minute. so just like before we can set up an equation to relate the values:
We are going to call this equation (2)
Since the total cost
of equations (1) and (2) is the same, we can equate them to find
:
We can conclude that after 3 additional minutes the cost of the calls will be the same; therefore, the correct answer is
B.