The total that Mary has initially is:
$6.00
Since the first 30 minutes cost $0.99, after those 30 minutes she will have:
$6.00 - $0.99 = $5.01
So far she has talked for 30 minutes but has $5.01 left.
After 30 minutes, the cost per minute is $0.04. To find the number of minutes that she can talk with those $0.04, we divide 5.01 by 0.04:
[tex]\frac{5.01}{0.04}=125.25[/tex]Using the remaining amount she can talk for 125.25 minutes more.
Thus, the total of minutes is:
[tex]30+125.25=155.25[/tex]Answer: She can talk for 155.25 minutes.
