What was the question for this implicit rationale, and corresponding answer?
The cost of one card from each box in total is 1.25 + 1.75 = 3 dollars. The total cost of cards the boy bought is 3 * 6 = 18 dollars.
 The answer: 18
The question: The card shop has two boxes of cards. The first box contains cards that cost $1.25 each. The second box contains cards that cost $1.75 each. A boy then comes in and buys 6 cards from each box. What was the total cost, in dollars, of the cards he bought?