#### Answer

a. $C(x)=18,000+20x$
b. $R(x)=80x$
c. (300, 24000)
When 300 canoes are sold, the revenue equals the cost =$\$ 24,000$

#### Work Step by Step

a.
Cost Function:$\quad C(x)=$ fixed cost $+$( cost per unit produced) $x$
$C(x)=18,000+20x$
b.
Revenue Function:$\quad R(x)=$( price per unit sold)$\cdot x$
$R(x)=80x$
c.
The point of intersection of the graphs of $R$ and $C$ is the break-even point (when R(x)=C(x) ).
$R(x)=C(x)$
$80x=18,000+20x\qquad/-20x$
$60x=18,000\qquad/\div 60$
$x=300$
$y=R(300)=80(300)=\$ 24,000$
(300, 24000)
When 300 canoes are sold, the revenue equals the cost =$\$ 24,000$