Cannon Precision Instruments makes an automatic electronic flash with Thyrister circuitry. The estimated marginal profit associated with producing and selling these electronic flashes is $P^{\text{'}}(x)=-0\mathrm{.}0025x20$ dollars per unit per month, when the production level is $x$ units per month.

Use geometry to calculate the definite integral, determining the change in profit over the sale of the first $8000$ electronic flashes. The graph of the marginal profit is provided for your use.