Answer:
$3, $11
Step-by-step explanation:
The profit function P(x) will be zero when either of its factors is zero. The left factor (x-3) is zero when x=3. The right factor (x-11) is zero when x=11.
Prices of $3 or $11 will result in $0 annual profit.
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Additional comment
A price halfway between these values, at (3+11)/2 = 7, will produce maximum profit, $32 million.
