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 $30 more, the corresponding ratio would have been 5:3. How much was the oil bill for January?	Select the correct option:
A) $120
B) $150
C) $180
D) $210
E) $240
3:2 = 9:6 and 5:3 = 10:6.   An increase in $30 increases the ratio by 1:6.   Therefore, January's bill was 6($30) = $180.   The answer is $180.
<result>C</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 $30 more, the corresponding ratio would have been 5:3. How much was the oil bill for January?