Cari German uses gas to heat her home.She has accumulated the following information regarding her monthly gas bill and monthly heating degree-days. The heating degree-days value for a month is found by first subtracting the average temperature for each day from 65 degrees and then summing these daily amounts together for the month.

Month	Heating Degree-Days	Gas Bill
February	1,900	$254
April	600	$101

The equation representing the relationship between the gas bill (Y) and heating degree-days (X) is