Question 1171901
x=each $1 and each 20 people
(11+x)(400-20x) product
find the maximum
-20x^2+180x+4400
maximum is where x=-b/2a, the vertex. That is -180/-40 or 4.5

$15.50 price and have 310 people (4.5*-20)
=$4805
always check on both sides
$16 and 300 people $4800
$15 and 320 people $4800
{{{graph(300,300,-20,30,-250,5000,4800,(11+x)(400-20x))}}}