Question 684479
She breaks even when profit = 0
Let {{{ P }}} = profit
Let {{{ n }}} = number of glasses sold

{{{ P = .25n - .15n - 20 }}}
{{{ P = .1n - 20 }}}
{{{ P = 0 }}}
{{{ .1n - 20 = 0 }}}
{{{ .1n = 20 }}}
{{{ n = 200 }}}
She must sell 200 glasses to break even