Question 150851
In words:
(liters of acid in beaker A) + (liters of acid in beaker B) / (total liters of solution in A and B) = % solution of acid
Let A = liters of solution needed from beaker A
Let B = liters of solution needed from beaker B
{{{(.15A + .2B) / (A + B) = .18}}}
Note that we are told {{{A + B = 6}}}liters
{{{(.15A + .2B) / 6 = .18}}}
Multiply both sides by {{{6}}}
{{{.15A + .2B = 1.08}}}
And since {{{A + B = 6}}}
{{{B = 6 - A}}}
{{{.15A + .2*(6 - A) = 1.08}}}
{{{.15A + 1.2 - .2A = 1.08}}}
{{{-.05A = -.12}}}
{{{A = 2.4}}}liters
Given is {{{A + B = 6}}}
{{{B = 6 - 2.4}}}
{{{B = 3.6}}}
2.4 liters of solution are needed from beaker A
and 3.6 liters of solution are needed from beaker B
check answer:
{{{(.15A + .2B) / 6 = .18}}}
{{{(.15*2.4 + .2*3.6) / 6 = .18}}}
{{{(.36 + .72) / 6 = .18}}}
{{{1.08 / 6 = .18}}}
{{{1.08 = .18*6}}}
{{{1.08 = 1.08}}}
OK