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?