Algebra question - Problem Solving?

Question

this was on my math test, and I want to know what the heck I did wrong.
Lady has $7000 to invest. One account at 3% interest the other at 8% interest, how much should she invest in the 2 accounts to obtain a 6% interest.

I think all I need to know is what I should've come up with an equation....My equation I put down was:

$7420 = [($7,000(7,000*.03x)(.03) + (7,000(7000*.08x)(.08)]1
Help!!!!!!! lol

Answer 1

3x/100 + (7000-x)*8/100=7000*6/100

3x+(7000-x)*8=42000
3x-8x=42000-56000
5x=14000

x=2800 in one bank
7000-x=4200 in another bank

Answer 2

You need to represent the unknowns (the amount to go into each account) with variables and added together, those unknowns equal 6% interest. So you have one side of the equation correct (7420), but the other side is a bit odd.

3% of something plus 8% of something else plus 7000 equals 7420.

Now, you create the equation and work it out...

Answer 3

Let's say the whole fraction is 1 and she invests x on 8% and this means that she invested 1-x on 3%
8%*7000x +3%*7000(1-x) = 6%*7000
560x + 210(1-x) = 420
560x + 210 - 210x = 420
560x-210x = 420 - 210
350x = 210
x = 210/350 = 0.6

This implies that she need 0.6*7000 on the 8% account
i.e. She will invest $4200 on 8% account and invest $2800 on the 3% account

Answer 4

I would have answered the question with this equation:
7420=1.08x + 1.03(7000-x)

If you solve it, you will find the amount that should be invested at 8% interest.

Alternately, if your teacher was looking for something with x and y variables, this would have been a possible set of equations:
7420=1.08x + 1.03y
y=7000-x

Answer 5

B/2 = -7 + B multiply the two components with the aid of two (*2)B/2 = 2(-7+B) simplify B = -14 + 2B subtract 2B from the two components B (-2B) = -14 + 2B (-2B) simplify -B = -14 divide with the aid of a adverse to isolate your variable -B/- = -14/- simplify B = 14 --------------------------------------... to study: placed your value for B that's 14 interior the equation the place B is placed 14/2 = -7+14 7 = 7 and the solutions are the comparable so that's actual