Question 1092339
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<pre>
Let x and y be amounts invested at 4% and 9%, respectively.


Then you have this system of equations

     x +      y = 17000,      (1)    (for total)
0.04*x + 0.09*y = 1380.       (2)    (for the amount earned)


By solving these equations, you can determine the unknown values x and y.


As a first step you can multiply eqn(1) bu 100 (both sides) to get

     x +      y =  17000,     (1)    (for total)
   4*x +    9*y = 138000.     (2)    (for the amount earned)


Next, you can express  one of the two unknowns from the eqn(1) and substitute to eqn(2). In this way you will get a single equation 
for one unknown, which you can easily solve.
It is how the Substitution method works.
</pre>

You can find many examples/samples of solved problems on investment in the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/coordinate/lessons/Using-systems-of-equations-to-solve-problems-on-investment.lesson>Using systems of equations to solve problems on investment</A>

in this site.


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this online textbook under the topic "<U>Systems of two linear equations in two unknowns</U>".



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.