Answer:
$800
Explanation:
You are going to want to use the simple interest formula for this. The one below is modified for solving the interest earned:

I = interest amount
P = principal amount
r = interest rate (decimal form)
t = time (years)
First, change 4% into its decimal form:
4% ->
-> 0.04
Now, lets plug in the values into the equation:


The interest earned after 20 years is $800