Question

Sergio's internet provider charges its customers $9 per month plus 4¢ per minute of on-line usage. Sergio received a bill from the provider covering a period and was charged a total of $81.40. How many minutes did he spend on-line during that period? (Round to the nearest whole minute, if necessary.)

Answer 1

9 + 0.04m = 81.40
0.04m = 81.40 - 9
0.04m = 72.40
m = 72.40 / 0.04
m = 1810 minutes <==