As the amount of food produced increases (as its supply rises), the exchange-value drops.
As a particular residence for elderly people in Brooklyn saw properties in its neighborhood rise in exchange-value, the landlord (who's primarily a businessperson, after all, motivated by profit) realized that s/he could make a great deal more money by evicting the elderly residents and converting the property into luxury condominiums.
In return they give or pester us with their services, which as such services have a use-value and because of their production costs also an exchange-value.
Domestic service might be drawn out over a lifetime whereas amusements are more often fleeting and hence do not exist 'in a more or less durable, and therefore again saleable, use-value' Marx, therefore, appreciates that exchange-value 'depends on the degree to which the use-value is durable, that is, on how slowly consumption deprives it of the possibility of being a commodity or bearer of exchange-value' (Marx, 1956: 294).
Although labour is common to all forms of capital and of value, each has its specific social dimension: use-values gain a social element if their utility is sought by someone other than their makers or current owners; value is a relation through the socially necessary labour-time required to achieve the average rate of profit; exchange-value 'is a relation between persons .
The social dimension of exchange-values exists while being compared with other goods or services: 'the commodity never has this form [exchange-value] when looked at in isolation, but only when it is a value-relation or an exchange relation with a second commodity of a different kind' (Marx, 1976: 152).
the exchange-value of things is a mere expression, a specific social form, of the productive activity of men, something entirely different from things and their use as things .
These associations are strained since not everything about each value-form fits with the proffered variants of spatio-temporality: use-value is more than extension when it is the bearer of exchange-value; the movements entailed in exchange-value depend on a prior comparison of values, leaving value no more 'relational' than exchange-value.
For example, labourers make cement, admixtures and sand into concrete slabs, a new use-value and the bearers of both more exchange-value and office towers.
The expansion of capital requires that the exchange-value of the steel in each new commodity be realised at the average rate of profit, or better.
Most significantly, Marx distinguished between labor-power, which is the productive capacity owned by the worker and purchased by the capitalist, and labor itself, which is the worker's productive activity and the source of a commodity's exchange-value