Question 1090440
They put the demand in order to trick you off on something behind it. 
<br>
So you might need to to use the suppy part

Price   Supply
$20      150
$30      250
$50      450

Then you might want to use the point slope form
<br>
{{{y-Supply=m(x-Price)}}}
<br> but you need to find the SLOPE and substitute so that it look like
{{{m=(250-150)/(30-20)}}} or {{{m=(450-250)/(50-30)}}}
and your answer should get {{{m=10}}}
<br>
Now you need to plug in the slope, supply and the price so you do this:

{{{y-150=10(x-20)}}} or {{{y-250=10(x-30)}}} or {{{y-450=10(x-50)}}}
<br>
Then multiply to get:
{{{y-150=10x-200}}} or {{{y-250=10x-300}}} or {{{y-450=10x-500}}}
<br>
You should get
<br>
{{{y=10x-50}}}<= Supply Equation
<br>
When you graph the supply equation, you should get
{{{graph(750, 750, -50, 50, -50, 50, 10x-50)}}}