investing: greatest amount in 6% fund to get $1500 or more

[sunshine25]

I just don't get it:

I am going to invest 20000 part and 6% and part at 8%. What is the most I can have at 6% to make at least $1500 in interest this year?

Please help me...

 

[Denis]

x = 6% portion

.06x + .08(20000 - x) = 1500 : OK?