.
Each day we solve 2-3-4 similar problems at this forum.
Therefore, I will give here only shortest version of the solution, referring for more complete solutions/explanations to the lesson
- Using systems of equations to solve problems on investment
in this site.
Solution
Let x = the amount invested at 7% annual simple interest.
Then the amount invested at 4% is (32000-x) dollars.
Your basic equation is
interest + interest = total interest, or
0.07x + 0.04*(32000-x) = 1670
Simplify and solve for x:
x = = 13000.
ANSWER. $13000 were invested at 7% and the rest, $32000- $13000 = $19000 were invested at 4%.
CHECK. 0.07*13000 + 0.04*19000 = 1670 dollars. ! Correct !
Solved and completed.
------------------
It is a standard and typical problem on investments.
As I just said, if you need more details, or if you want to see other similar problems solved by different methods, look into the lesson
- Using systems of equations to solve problems on investment
in this site.
You will find there different approaches (using one equation or a system of two equations in two unknowns), as well as
different methods of solution to the equations (Substitution, Elimination).
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lesson is the part of this online textbook under the topic "Systems of two linear equations in two unknowns".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.