Under his cell phone plan, Parker pays a flat cost of $47.50 per month and $3 per
gigabyte, or part of a gigabyte (For example, if he used 23 gigabytes, he would have
to pay for 3 whole gigabytes.) He wants to keep his bill under $60 per month. What is
the maximum whole number of gigabytes of data he can use while staying within his
budget?