Write an equation to find the amount of simple interest, earned on a 600 dollar investment after 9 months, of the interest rate is 2.5%

Equation:

A = P (1 + rt)

How to do it:

First, converting R percent to r a decimal

r = R/100 = 2.5%/100 = 0.025 per year,

putting time into years for simplicity,

9 months : 12 months/year = 0.75 years,

then, solving our equation

A = 600 (1 + (0.025 * 0.75)) = ___

What is it?