Question 400613
In words:
(sand in final mixture)/(sand + soil in final mixture) = 31%
Let {{{x}}} = pounds of her soil she used
given:
{{{.28x}}} = pounds of sand in her soil
{{{.33*6 = 1.98}}} pounds of sand in commercial potting soil
--------------------------
{{{(.28x + 1.98)/(6 + x) = .31}}}
{{{.28x + 1.98 = .31*(6 + x)}}}
{{{.28x + 1.98 = 1.86 + .31x}}}
{{{.03x = .12}}}
{{{x = 4}}}
She needs 4 pounds of her soil
check:
{{{(.28*4 + 1.98)/(6 + 4) = .31}}}
{{{(1.12 + 1.98)/10 = .31}}}
{{{3.1/10 = .31}}}
{{{3.1 = 3.1}}}
OK