For this story problem I have to:
1.) choose a variable and indicate what it represents,
2.) write a complex equation using that variable,
3.) solve the equation.

Alex invested part of his $38,000 advance at 6% annual simple interest, and the rest at 4% annual simple interest. If his total yearly interest from both accounts
was $2000, find the amount invested at EACH rate.

Let x be the amount of money invested at 6%
Let y be the amount of money invested at 4%
Then x+y should equal the total amount invested - $38,000.
The product of the interest rates and the amounts invested should yield the yearly interest from both accounts - $2000.

You get:
x+y = 38000
.06x + .04y = 2000

I leave solving the system to you

heh, i took that to mean something very different I guess

yeah lol I was fucking confused at first

Substitute: y = 38000 - x so that you only have one variable

.06x + 0.4 (38000 - x) = 2000 where x is the amount invested at 6%