the appropriate formula to use here is
A = P (1 + r)^t,
where A is the final amount, P is the initial amount, r is the annual interest rate as a decimal fraction, and t is the number of years (number of compounding periods).
Substituting the givens: $35000 = P(1+0.036)^3
$35000
Solving for P: P = ----------------- = $31476.67 (answer)
(1.036)^3