Question 198073
Let {{{x}}}= ft3 of 45% sand soil needed
In words:
{ft3 sand in final mixture)/(total ft3 of mixture) = 35%
{{{(.45x + .15*1) / (x + 1) = .35}}}
Multiply both sides by {{{x + 1}}}
{{{.45x + .15 = .35*(x + 1)}}}
{{{.45x + .15 = .35x + .35}}}
{{{.1x = .2}}}
{{{x = 2}}}
2 ft3 of 45% sand soil is needed
check:
{{{(.45*2 + .15*1) / (2 + 1) = .35}}}
{{{(.9 + .15) / 3 = .35}}}
{{{1.05/3 = .35}}}
{{{.35 = .35}}}
OK