Question 138848
Let {{{w}}}= mass of whole wheat flour
Let {{{b}}}= mass of organic barley flour
{{{w + b  = 20}}} kg
{{{b = 20 - w}}}
{{{(2.19w + 1.89b) / 20 = 1.99}}}
{{{2.19w + 1.89b = 20*1.99}}}
{{{2.19w + 1.89*(20 - w) = 39.8}}}
{{{2.19w + 37.8 - 1.89w = 39.8}}}
{{{.3w = 2}}}
{{{w = 6.67}}}
{{{b = 20 - 6.67}}}
{{{b = 13.33}}}
6.667 kg of the whole wheat anfd 13.333 kg of the barley are needed
check:
{{{2.19*6.67 + 1.89*13.33) / 20 = 1.99}}}
{{{(14.6 + 25.2) /20 = 1.99}}}
{{{39.8 / 20 = 1.99}}}
{{{1.99 = 1.99}}}