The ratio of the amount of the oil bill for the month of February to the amount of the oil bill for the month of January was 3:2. If the oil bill for February had been $20 more, the corresponding ratio would have been 5:3. How much was the oil bill for January?
Choices:	A) $100	B) $120	C) $140	D) $160	E) $180
3:2 = 9:6 and 5:3 = 10:6.   An increase in $20 increases the ratio by 1:6.   Therefore, January's bill was 6($20) = $120.   The answer is $120.
<result>B</result>
The ratio of the amount of the oil bill for the month of February to the amount of the oil bill for the month of January was 3:2. If the oil bill for February had been $20 more, the corresponding ratio would have been 5:3. How much was the oil bill for January?