Question 1129563

Santos invests ${{{7700}}} in two different accounts. 

let's say {{{x}}} is one account and {{{y}}} is other account


The first account paid {{{11}}} %, ={{{0.11}}}

the second account paid {{{2}}} % in interest={{{0.02}}}


At the end of the first year he had earned ${{{424}}} in interest.


{{{x+y=7700}}}........eq.1->both sides multiply  by {{{11}}}
{{{0.11x+0.02y=424}}}......eq.2->both sides multiply  by {{{100}}}
--------------------------------------------------
{{{11x+11y=84700}}}........eq.1
{{{11x+2y=42400}}}......eq.2
----------------------------------------------------subtract
{{{11x+11y-11x-2y=84700-42400}}}
{{{cross(11x)+11y-cross(11x)-2y=42300}}}
{{{9y=42300}}}
{{{y=42300/9}}}
{{{y=4700}}}

then,
{{{x+y=7700}}}...plug in {{{y}}}
{{{x+4700=7700}}}
{{{x=7700-4700}}}
{{{x=3000}}}


 How much was in each account? 
At {{{11}}}%- was {{{3000}}}-> got {{{330}}} in interest
At {{{2}}}%-  was {{{4700}}} -> got {{{94}}} in interest