Question: Can you break down the solution for me for this math problem: 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?
Answer: 
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.