Solve
-A Common Equation Used in Business Is a Demand $p = - x ^ { 2 } + 88$

Solve.
-A common equation used in business is a demand equation. It expresses the relationship between the unit price of some commodity and the quantity demanded. In the demand equationon $p = - x ^ { 2 } + 88$ , for a certain style of
Calculator, p is the price per calculator in dollars and x is the quantity demanded in thousands. Find the demand
For the calculator if the price is $7 per calculator.

A) 9 thousand units
B) 10 thousand units
C) $40 \frac { 1 } { 2 }$ thousand units
D) 39 thousand units