Answer: she was billed for 120 extra minutes.
Explanation:
Let x represent the total number of minutes that Jane used.
Jane's cell phone plan is $40 a month plus $0.15 per minute for each minute over 200 minutes. Thus means that the total cost for x minutes on the phone would be
40 + 0.15(x - 200)
40 + 0.15x - 30
0.15x + 40 - 30
0.15x + 10
If Jane's cell phone bill Is $58.00, it means that
0.15x + 10 = 58
0.15x = 58 - 10 = 48
x = 48/0.15 = 320
The total number of minutes that she used is 320.
The total number of extra minutes for which she was billed is
320 - 200 = 120