Question 613262
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi, 
R(x) = 55x - 2x^2 
C(x) = 21x + 98
P(x) = 55x - 2x^2 -(21x + 98)
P(x) = -2x^2 + 34x - 98
  x = 8.5 makes max profit
{{{drawing(300,300,   -3,20,-10,50, 
 grid(1),
circle(8.5, 46.5,0.4),
graph( 300, 300, -3,20,-10,50,0, -2x^2 + 34x - 98))}}}