Question 700506
Profit is ( income ) - ( costs )
{{{  P = I - C }}}
Let {{{ x }}} = number of buttons sold
{{{ I = 1.5x }}}
{{{ C = 25 + 50 }}}
{{{ C = 75 }}}
{{{ P = 1.5x - 75 }}}
(a)
When profit = 0
{{{ 0 = 1.5x - 75 }}}
{{{ 1.5x = 75 }}}
{{{ x = 50 }}}
If he sells 50 buttons, he breaks even
(b)
{{{ P = 1.5x - 75 }}}
{{{ P = 1.5*135 - 75 }}}  
{{{ P = 202.5 - 75 }}}
{{{ P = 127.5 }}}
His profit is $127.50