<PRE><B>Question 314449</B>
Let x=amount invested at 8%
Let y=amount invested at 12%


You have two variables, so you need two equations.


Equation 1: x+y=20000   (the sum of her initial investments)
Equation 2: 0.08x + 0.12y = 1836.88  (the sum of her investment earnings)


Now you can isolate for x or y in Equation 1. I will choose to isolate for x:


x=20000-y


Now substitute this value into Equation 2, and then solve for y:


0.08(20000-y) +0.12y = 1836.88
1600-0.08y +0.12y = 1836.88
1600 +0.04y = 1836.88
0.04y = 236.88
y=5922


Now plug this y value into Equation 2 to find x:


x=20000-y
x=20000-5922
x=14078</PRE>