Answer:
<h2>39 minutes</h2>Step-by-step explanation:
In this problem we can see that there is a constant/flat rate charge of $4 on every first minute
we can model the cost for calls as
where x is the number of extra minutes spent
given that y = $13.75
We can simply substitute our given values into the equation 1 above and solve for x
Divide both sides by 0.25 to find x