Question 432501
In words:
(liters of pure baking soda in final solution)/(liters of final solution) = 70%
Let {{{x}}} =  liters of pure baking soda to be added
given:
Pure baking soda in 40% solution is {{{ .4*180 = 72 }}}
-----------------
{{{ (x + 72)/(x + 180) = .7 }}}
{{{ x + 72 = .7*(x + 180) }}}
{{{ x + 72 = .7x + 126 }}}
{{{ .3x = 54 }}}
{{{ x = 180 }}}
180 liters of pure baking soda must be added
check:
{{{ (x + 72)/(x + 180) = .7 }}}
{{{ (180 + 72)/(180 + 180) = .7 }}}
{{{ 252 / 360 = .7 }}}
{{{ .7 = .7 }}}
OK