SOLUTION: An amount of money is invested at 4% annual simple interest, and twice that amount is invested at 5%. The total annual interest is $112. How much is invested at each rate?

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Question 177654This question is from textbook intermediate algebra
: An amount of money is invested at 4% annual simple interest, and twice that amount is invested at 5%. The total annual interest is $112. How much is invested at each rate? This question is from textbook intermediate algebra

Answer by MathTherapy(10552) About Me  (Show Source):
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Let the amount being invested at 4% be f
Then the amount invested at 5% is 2f
As I = PTR, then (f.1..04) + (2f.1..05) = 112
.04f + .1f = 112
.14f = 112
f = 112 ÷ .14 = $800
Therefore, $800 is invested at 4%, while $1,600 is invested at 5%.
Checking:
(800 . 1 . .04) + (1,600 . 1 . .05) = 32 + 80 = $112