Question 892343
In words:
cost / kg = ( cost of sbo  + cost of co ) / ( kg of sbo + kg of co )
Cost / kg = {{{ ( 7*4 + 14*1 ) / ( 7 + 14 ) }}}
Cost / kg = {{{ ( 28 + 14 ) / 21 }}}
Cost / kg = {{{ 42 / 21 }}}
Cost / kg = {{{ 2 }}}
$2 / kg