One year ago Wadi invested a total of $2,000 in three separate accounts. One account pays 3% annual interest, another pays 6%, and the final account pays 8% annual interest. He has four times as much invested at 8% as he does at 3%. Wadi made a total of $135 in interest in one year. How many dollars did Wadi invest in the account that pays 6% interest?

Wadi invested _____ dollars into that account.