SOLUTION: I have story problems I have to get an equation for and solve. I try to draw out tables to help me figure out the equations but I have a rough time finding the right spot to put e

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Question 560131: I have story problems I have to get an equation for and solve. I try to draw out tables to help me figure out the equations but I have a rough time finding the right spot to put everything in. Can you help me?
Here is the problem:
A certain sum of money is invested at 6.35%, and $4000 more than that amount is invested at 7.28%. If the annual interest from the two investments is $972.70, how much was invested at 6.35%?

My table I made using the formula I=P*R*T
I = P * R * T
INVEST 1 635X X 635 1
INVEST 2 728(4000-X) 4000-X 1
TOTAL 972.70 4000
Can you please explain what I did wrong and how to do it right and show me what the equation is?
Thanks!! :)
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
A certain sum of money is invested at 6.35%, and $4000 more than that amount is invested at 7.28%.
If the annual interest from the two investments is $972.70, how much was invested at 6.35%?
:
Let's do it this way
Let x = amt invested at 6.35%
then it says,"$4000 more than that amount, is invested at 7.28%." therefore
(x+4000) = amt invested at 7.28%
;
.0635x + .0728(x+4000) = 972.70; this is the equation you want
.0635x + .0728x + 291.20 = 972.70
.0635x + .0728x = 972.70 - 291.20
.1363x = 681.50
x =
x = $5000 invested at 6.35%
;
:
Check the solution by finding the amt invested on each one
.0635*5000 = 317.50
.0728*9000 = 655.20
===================
total int: = 972.70