CEVAP:

For example, when the planned expenditure is greater than the value of current
production, production will increase to meet the demand for goods and services. The fact that aggregate expenditures are greater than GDP means that more than the amount of goods and services currently produced in the economy is planned to
purchase. To meet this demand, firms sell goods and services that they have produced in the past and are waiting in stock. In other words, if the planned expenditures are greater than GDP, firms’ stocks decrease. The change in stocks compensates
the planned expenditure exceeding the GDP. Thus, actual expenditures, including unplanned changes in stocks, are equalized to GDP. Decreasing stocks will cause firms to increase their production. Thisincrease in production will cause an increase in
income or GDP. If the total expenditures are less than GDP, the entire goods and services produced in the economy will not be bought, and the stocks of the firms will start to increase. In this case, firms that cannot sell the goods and services they produce will preduce their production. This decrease in production will lead to a decline in income or GDP.