Add up minutes
1stmonth+2ndmonth+3rdmonth=320+243+489=1052
how many 200's are there
6 of them (companies want money so they see, ok, you bought like 1 minute, we will charge you for the whole 200 minutes since you got in that zone)
6 times 25=150
cost is $150 (mom is not going to be happy, she spend like 3% of her waking hours takling on the phone)
The abswer for first question is x=14y+−12
second is x=−12y+−32
