Question

Ponco charges phone users $1.25 for the first minute and $0.30 for each additional minute.Cowbell charges users $1.40 for the first minute and $0.25 for each additonal minute. How many additional minutes will it take for the cost of the calls to be the same?

Answer 1

We are going to denote the number of additional minutes with $x$, and the total cost of the call with $y$. 

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 $x$ and our total cost of the call is $y$, we can set up an equation to relate the values:
$1.25+0.30x=y$ 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:
$1.40+0.25x=y$ We are going to call this equation (2)

Since the total cost $y$ of equations (1) and (2) is the same, we can equate them to find $x$:
$1.25+0.30x=1.40+0.25x$
$0.05x=0.15$
$x= \frac{0.15}{0.05}$
$x=3$

We can conclude that after 3 additional minutes the cost of the calls will be the same; therefore, the correct answer is B.