Question 762875
Let {{{ x }}} = number of days he worked
{{{ 20 - x }}} = the number of days he was idle
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given:
{{{ 5680 = 300x - 80*( 20 - x ) }}}
{{{ 5680 = 300x - 1600 + 80x }}}
{{{ 380x = 5680 + 1600 }}}
{{{ 380x = 7280 }}}
{{{ x = 19.158 }}}
He worked 19.158 days
check:
{{{ 5680 = 300x - 80*( 20 - x ) }}}
{{{ 5680 = 300*19.158 - 80*( 20 - 19.158 ) }}}
{{{ 5680 = 5747.368 - 80*.842 }}}
{{{ 5680 = 5747.368 - 67.36 }}}
{{{ 5680 = 5680.008 }}}
OK -error must be due to rounding off