if a housewife has meat and tomatoes, she must find someone who wants meat and has tomatoes to give. this concept is described as?

Step 1: Analyze the question A housewife has meat and wants tomatoes. To get them, she must find someone who has tomatoes and wants meat. This is exchange without money, which is barter trade.

Step 2: The concept In a barter system, a trade happens only if both parties want what the other has. This requirement is called the double coincidence of wants. It is the main weakness of barter, and it is why money was introduced as a medium of exchange.

Step 3: Check each option

• A. Opportunity cost is the value of the next best alternative given up when making a choice. It has nothing to do with finding a trading partner.
• B. Scale of preference is a list of a person's wants arranged in order of importance. It is not relevant here.
• C. Complementary demand is the demand for goods used together, such as tea and sugar. This is not what the question describes.
• D. Double coincidence of wants matches the situation exactly. Her wants (tomatoes) and her offer (meat) must match the other person's wants (meat) and offer (tomatoes).

Answer: D. Double coincidence of wants (the option is misspelled "double of coincidence of wants", but that is clearly what it means).

Exam tip: If you see "I have X and want Y, so I must find someone who has Y and wants X", think barter → double coincidence of wants. It is a very common WASSCE and JAMB question.