Xavier claims that the number of text messages he sends is proportional to the amount he owes on his monthly phone bill. He made a list of the number of text messages he sent and the amount he owed f

Xavier claims that the number of text messages he sends is proportional to the amount he owes on his monthly phone bill.  He made a list of the number of text messages he sent and the amount he owed for the first four months.

• January: 300 text messages sent; $15.00 owed
• February: 314 text messages sent; $15.70 owed
• March: 486 text messages sent; $24.30 owed
• April: 205 text messages sent; $10.25