Question 758716
{{{ 7 + 14 = 21 }}} kg of total mixture
{{{ 7*4 = 28 }}} = cost of $4/kg oil
{{{ 14*1 = 14 }}} = cost of $1/kg oil
------------------------------
{{{ ( 28 + 14 ) / 21 = 42/21 }}}
{{{ 42/21 = 2 }}}
The cost /kg of the mixture is $2