Question 228905
In words:
(ounces of salt in final solution)/(water + salt in final solution) = 15%
Let {{{a}}} = ounces of salt in 10% solution
given:
{{{a/(90 + a) = .1}}}
{{{a = .1*(90 + a)}}}
{{{a = 9 + .1a}}}
{{{.9a = 9}}}
{{{a = 10}}}
Let {{{b}}} = ounces of water in a 15% solution
{{{10/(10 + b) = .15}}}
{{{ 10 = .15*(10 + b)}}}
{{{10 = 1.5 + .15b}}}
{{{.15b = 8.5}}}
{{{b = 56.667}}}
I started with {{{90}}} ounces of water, so the decrease must be
{{{90 - 56.667 = 33.333}}} ounces