Answer:
11 minutes?
Explanation:
A five-minute difference in the two calls results in an increase of
10.86 - 5.91 = $4.95
That means the company charges $4.95 / 5 = $.99 a minute.
The original five-minute call costs $4.95 plus another $.96. That's how they got $5.91 for its charge.
Thus the equation for this situation is (using C for cost and m for minutes)
C = .99m + .96
Now plug 12 in for C and get
12 = .99m + .96
m = 11.15 minutes...probably rounded to 11 minutes...