SOLUTION: Two investments totaling $31,000 produce an annual income of $2635. One investment yields 7% per year, while the other yields 10% per year. How much is invested at each rate?

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Question 950503: Two investments totaling $31,000 produce an annual income of $2635. One investment yields 7% per year, while the other yields 10% per year. How much is invested at each rate?
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
a+b= 31000. Thus, a= 31000-b (1)
.07a + .10b = 2,635 (2)
Now let's substitute in (2) with what we learned in (1)
.07(31000-b) + .10b = 2,635 Now let's multiply on the left:
2170 - .07b + .10b = 2635 Next, subtract 2170 from both sides and add the left:
.03b = 465 Divide both sides by .03:
b = 15,500 This is the amount invested at 10%, and 31000-15500= 15500 is invested at .07.