SOLUTION: Mr. Jones has $10,000 to invest. He invests part at 6% and the rest at 8%. If he earns $680 in interest after 1 year, how much did he invest at each rate?

Question 1111406: Mr. Jones has $10,000 to invest. He invests part at 6% and the rest at 8%. If he earns $680 in interest after 1 year, how much did he invest at each rate?
Answer by ikleyn(52776) (Show Source): You can put this solution on YOUR website!
.

Your equation is

0.06*x + 0.08*(10000-x) = 680,


where "x" is the amount of the 6% investment.


Solve for x:

0.06x + 800 - 0.08x = 680

-0.02x = 680 - 800 = -120  ====>  x =  = 6000.


Answer.  $6000 was invested at 6%.  The rest  $10000-$6000 = $4000 was invested at 8%.


Check.   0.06*6000 + 0.08*4000 = 680 dollars.   ! Correct !

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If you want more details or if you want to see other similar solved problems, 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.

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