SOLUTION: Sally invested a certain sum of money at 9%, twice that sum at 10%, and three times that sum at 11%. Her total yearly interest from all three investments was $310. How much did s

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Question 75481This question is from textbook Elementary algebra
: Sally invested a certain sum of money at 9%, twice that sum at 10%, and three times that sum at 11%. Her total yearly interest from all three investments was $310. How much did she invest at each rate?
Thanks...can't seem to figure out three loans.
 This question is from textbook Elementary algebra

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
let x equal the certain sum...she invested x at 9%, 2x at 10%, and 3x at 11%...so the total interest would be (x*.09)+(2x*.10)+(3x*.11)

this means that .62x=310...so x=500

Sally invested $500 at 9%, $1000 at 10%, and $1500 at 11%