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 5:4. If the oil bill for February had been $45 more, the corresponding ratio would have been 3:2. How much was the oil bill for January? Pick one: A) $ 60 B) $ 90 C) $ 120 D) $ 150 E) $ 180

Rationale: 5 : 4 = 15 : 12 and 3 : 2 = 18 : 12 . an increase in $ 45 increases the ratio by 3 : 12 . therefore an increase in $ 15 increases the ratio by 1 : 12 . therefore , january ' s bill was 12 ( $ 15 ) = $ 180 . the answer is e .
Answer: E