Mr. Johnson has invested $30,000 part @ 4% and part @ 7%. His annual interest from the two investments is $1500. How much is invested @ each rate?
So far I have the first equation, I think, but I can't figure out how to write the second part. This is what I've set up already:
.4x + .7y=30000
In order to solve for x and y, I still need to figure out the second equation. Any ideas?
1. You don't need a second variable, if you calculate the value of the second part as ($30.000 - x).
2. You used the wrong values: 0.4 = 40%. If you aren't sure that you have done the transformation percent --> fraction correctly than use fractions with the denominator 100. So 4% = 4/100.
OK, once again:
Let x denote the part of the $30.000 which is invested at 4 %;
then y are invested at 7 %.
Now you know:
Solve the first equation for and plug this term into the second equation:
Expand the bracket, collect like terms, solve for x.
Resubstitute the value of x into the equation calculating y.
You already know the results.