To find: The amount invested at interest rate
The amount invested at
Given:
Phyllis invested a portion of $12,000 at a rate of
The interest earned after 1 year is $525.
Calculation:
Let the amount invested at
Tabulate the given information into the language of algebra.
In words  In Algebra 
Amount invested at
 x 
Amount invested at 4% 

Interest earned at
 0.045x 
Interest earned at 4% 

Model the equation for the above information.
Simplify the above equation for x,
The amount invested at 4% rate is,
Thus, the amount invested at