Question 705316
I will plot {{{ P }}}, production volume, on the
vertical axis and {{{ C }}}, cost, on the 
horizontal axis.
---------------
I will use the general point-slope formula:
{{{ ( P - 50 ) / ( C - 100 ) = ( 100 - 50 ) / ( 150 - 100 ) }}}
{{{ ( P - 50 ) / ( C - 100 ) = 50 / 50 }}}
{{{ P - 50 = C - 100 }}}
{{{ P = C - 50 }}}
--------------
check answer:
( $100, 50 )
{{{ P = C - 50 }}}
{{{ 50 = 100 - 50 }}}
{{{ 50 = 50 }}}
OK
------
( $150, 100 )
{{{ P = C - 50 }}}
{{{ 100 = 150 - 50 }}}
{{{ 100 = 100 }}}
OK
-------
Here's the plot:
{{{ graph( 400, 400, -30, 200, -10, 150, x - 50 ) }}}