Answer
\$20
\$4
10
\$60
\$80
Work Step by Step
The vertical intercept is the cost when 0 Frisbee's are produced, \$20.
$Slope=\frac{\Delta y}{\Delta x}=\frac{60-20}{10-0}=\frac{40}{10}=4$
Point b is the intersection of 10 Frisbees per day on the x-axis and \$60 on the y-axis.
The cost of producing 15 Frisbees can be computed using the slope and a given point, for example 10 Frisbees at a cost of \$60.
$4=\frac{F-60}{15-10}$
$4=\frac{F-60}{5}$
$4\times 5=\frac{F-60}{5}\times5$
$20=F-60$
$20+60=F-60+60$
$80=F$
