Question 1155580
{{{ P(x)  = -x^2 + 980x - 3000 }}}
The formula for the x-value of the vertex 
( maximum in this case ) is:
{{{ x[max] = -b/(2a) }}}
{{{ x[max] = -980/( 2*(-1)) }}}
{{{ x[max] = 490 }}}
Plug this result back into equation:
{{{ P( 490 ) = -(490)^2 + 980*490 - 3000 }}}
{{{ P( 490 ) = -240100 + 480200 - 3000 }}}
{{{ P( 490 ) = 237100 }}}
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There maximum ;profit is $237,000
and the number of virtual pets sold
is 490
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check:
Here's the plot:
{{{ graph( 600, 600, -500, 1000, -30000, 300000, -x^2 + 980x - 3000 ) }}}
Looks about right