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Let x = "How much did she invest in Fund B".
Then the amount she invested in fund A was (x-8000) dollars.
Fund A returned 0.03*(x-8000) dollars.
Fund B returned 0.07*x dollars.
According to the condition,
0.03*(x-8000) + 0.07x = 1960.
Simplify and solve for x.
0.03x - 0.03*8000 + 0.07x = 1960
0.1x = 1960 + 240
0.1x = 2200 ====> x = = 22000.
Answer. $22000 was invested in fund B.
Check. 0.03*(22000 - 8000) + 0.07*22000 = 1960 dollars. ! Correct !
Solved.
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It is a typical and standard problem on investment.
If you want to learn on how to solve such problems on your own, 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.