Chapter 3 - Section 3.2 - Problem Solving and Business Applications Using Systems of Equations - Exercise Set - Page 205: 17

$x=17000,y=3000$

Given: $x+y=20000$ and $0.12x-0.05y=1890$ After plugging the variable $x$ form the first equation in the second equation, we get $0.12(20000-y)-0.05y=1890 \implies -0.17y=-510$ or, $y=3000$ Now, $x+3000=20000$ or, $x=20000-3000=17000$ Thus, $x=17000,y=3000$