You invested $10,000 in two accounts 7% and 8% annual interest, respectively. If the total interest earned for the year was $720, how much was invested at each rate?
HELPPPP

Question

You invested $10,000 in two accounts 7% and 8% annual interest, respectively. If the total interest earned for the year was $720, how much was invested at each rate?
HELPPPP

tkhunny · Answer

How much is invested at 7%?  If you don't know, NAME it!

anonymous · Answer

I don't get what you mean!!

tkhunny · Answer

We need the amount in the 7% Account.  We don't know it.  Call it "S".
We need the amount in the 8% Account.  We don't know it.  Call it "E".

Once we have defined these terms, we can now talk about them.

Express $10,000 in terms of S and E.
Express the total interest earned in terms of S and E.

anonymous · Answer

okay so
 s+e=10,000
.7s+.8e=720 
is this right??

tkhunny · Answer

So close!  0.07S + 0.08E = 720

Now, solve the system.

The important part was NAMING things.  Pretty simple, isn't it?