How do you calculate the area underneath the demand curve when it asks what the total value is

Total utility

Explanation:

The demand curve gives the amount acceptable to the consumers as price for a given quantity of a product. That is to say, given the available quantity of a product, the height of the demand curve gives the amount the consumers estimate the worth of the product

The area under the demand curve, therefore, represents the amount of utility or satisfaction that can be derived from a good or service, given that the demand curve is the representation of the estimation of the worth of a good by a consumer and price that the consumers pay is the utility cost

a manufacturer of printed circuit boards uses exponential smoothing with trend to forecast monthly demand of its product. at the end of december, the company wishes to forecast sales for january. the estimate of trend through november has been 200 additional boards sold per month. average sales have been around 1000 units per month. the demand for december was 1100 units. the company uses α = 0.20 and β = 0.10. make a forecast including trend for the month of january.