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 $10 more, the corresponding ratio would have been 5:3. How much was the oil bill for January?
Choose the correct choice from the following answers:	A) $60	B) $80	C) $100	D) $120	E) $140
3:2 = 9:6 and 5:3 = 10:6.   An increase in $10 increases the ratio by 1:6.   Therefore, January's bill was 6($10) = $60.   The answer is $60.
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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 $10 more, the corresponding ratio would have been 5:3. How much was the oil bill for January?