SOLUTION: Roberto invested some money at 7%, and then invested $3000 more than twice this amount at 10%. His total annual income from the two investments was $3810. How much was invested at

Question 168004: Roberto invested some money at 7%, and then invested $3000 more than twice this amount at 10%. His total annual income from the two investments was $3810. How much was invested at 10%?
P.S. I am assuming that this is to be translated into an actual formula in order to obtain the answer, but I can get really frustrated with almost all word problems. Please help me. Thank you.
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Once you call the unknown by a letter, it falls into place, usually
Let = the amount invested at 7%
Then it gives you
= the amount invested at 10%
Now the problem wants to know how much was made from the 2 investments
Think of this as the profit.

This was the amount invested @ 7%

This was the amount invested @ 10%
check:

OK
He invested $10,800 @ 10%

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