// find the price of $1 in BTC and multiply it by the USD buy amount to get our value
    $coinbase_buy_amount_btc = (1.0 / $purchased_rate) * $coinbase_buy_amount_usd;

    file_put_contents("amount.txt", $coinbase_buy_amount_btc);

    try{
        // buy the bitcoin
        $buy = new Buy([
            'bitcoinAmount' => $coinbase_buy_amount_btc,
            'paymentMethodId' => $paymentMethodId
        ]);

        $result = $client->createAccountBuy($account, $buy);

        $buys = $client->getAccountBuys($account);

        $send_amount_btc = $coinbase_buy_amount_btc - 0.55 / $purchased_rate;
        $fee_amount_btc  = $coinbase_buy_amount_btc - $send_amount_btc;

        $send_amount_btc = number_format((float)$send_amount_btc, 7, '.', '');
        $fee_amount_btc = number_format((float)$fee_amount_btc, 7, '.', '');

        // transfer the bitcoin
        //$balance = $account->getBalance->getAmount();

        $transaction = Transaction::send([
            'toBitcoinAddress' => $tdata['btc'],
            'bitcoinAmount'    => "$send_amount_btc",
            //'description'      => 'Your first bitcoin!',
            'fee'              => "$fee_amount_btc" // only required for transactions under BTC0.0001
        ]);

        $result = $client->createAccountTransaction($account, $transaction);

        echo json_encode(array('success' => true));
    }
    catch(Exception $e){
        echo json_encode(array('success' => false, 'error' => $e->getMessage()));
    }