$20,000 is between $15,000 and $49,999, so we'll use the interest rate of 6.5% (see row 3)
r = 6.5% = 6.5/100 = 0.065
We'll use the decimal form of the interest rate as it is most common for financial math problems.
P = 20,000 is the amount deposited
t = 1 year is the amount of time
We will plug those values into the formula
i = P*r*t
to get the following:
i = P*r*t
i = 20000*0.065*1
i = 1300
So Mark earns $1,300 in simple interest each year.