How many ether user eventually get after trading in this smart contract?

Question

I'm exploring method trade of this smart contract that looks like the following:

  function trade(address tokenGet, uint amountGet, address tokenGive, uint amountGive, uint expires, uint nonce, address user, uint8 v, bytes32 r, bytes32 s, uint amount) {
      //amount is in amountGet terms
      bytes32 hash = sha256(this, tokenGet, amountGet, tokenGive, amountGive, expires, nonce);
      if (!(
              (orders[user][hash] || ecrecover(sha3("\x19Ethereum Signed Message:\n32", hash), v, r, s) == user) &&
              block.number <= expires &&
              safeAdd(orderFills[user][hash], amount) <= amountGet
          )) throw;
      tradeBalances(tokenGet, amountGet, tokenGive, amountGive, user, amount);
      orderFills[user][hash] = safeAdd(orderFills[user][hash], amount);
      Trade(tokenGet, amount, tokenGive, amountGive * amount / amountGet, user, msg.sender);
  }

Could you please answer the following questions:

1. What's difference between amountGet and amount arguments?
2. How can I eventually know how many ETH user got when selling ARC token in this transaction ? Does amountGive give me this value?

Decoded input of this transaction is:

  inputs: [
        '0xac709fcb44a43c35f0da4e3163b117a17f3770f5',
        '2500000000000000000000',
        '0x0000000000000000000000000000000000000000',
        '13775000000000000000',
        '3156959',
        '3696351802',
        '0xd8eeda4ee2657bb267bc35c1d60babdc5aedd269',
        '28',
        'b4bf0dcd37ca73bd5abce9532b033dcc6427be160683de113efca41320c27f3e',
        '78799d84040e5c245828b1b531ef97e1af124946f4dc1db5a20cf28a7073b269',
        '726181804936299500000'
    ]

Thanks for your answers in advance!

Answer 1

1. amountGet is how much the maker of the order is willing to buy. amount is how much the taker of the order is willing to sell.

2. amount is the amount that gets traded. amountGet is only used to locate the order by its hash. The amount of tokenGive (ETH in this case) that the transaction sender gets is amount * amountGive / amountGet.