Question 42640
Define {{{y}}} as total payment:
{{{D = -5p + 40}}}
also known as
{{{y = -5p + 40}}}
and
{{{S =  -p^2 + 30p - 8}}}
also known as
{{{y = -p^2 + 30p - 8}}}
Combine:
{{{y = -p^2 + 30p - 8}}} while you know that {{{y = -5p + 40}}}
{{{-5p + 40 = -p^2 + 30p - 8}}}
{{{0 = -p^2 + 35p - 48}}}
*[invoke quadratic "p", -1, 35, -48]
{{{ graph( 600, 600, -5, 35, -150, 100, -5x + 40, -x^2 + 30x - 8) }}}