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

The concept described in the given scenario is called "double coincidence of wants." It refers to the situation where two parties have goods or services that the other party desires and are willing to exchange, and both parties are able to meet each other's wants at the same time. In the example, the housewife wants tomatoes, and she has meat that she can offer in exchange. However, she can only trade with someone who has tomatoes and also wants meat. The double coincidence of wants occurs when both parties have what the other wants, and both are willing and able to trade. This concept is important in understanding how bartering works, which is an exchange of goods and services without the use of money.