Give the step-by-step reasoning process and then the final answer. Betty bought 1 kg of oranges and 3 kg of apples. The total cost of oranges was $12. The apples were two times cheaper than the oranges. How much did Betty pay for 1 kg of apples?
The cost of the apples was $12 / 2 = $6. When the cost of 3 kg of apples was $6, then the cost of 1 kg of apples was $6 / 3 kg = $2 / kg.
The final answer: 2.