Theo is considering going to his friend's birthday party for 2 hours and his enjoyment from the party is $924. To attend the party, he has to buy a present that costs $W and he will have to cancel his 2-hour private tutoring job that pays HK$474 per hour. Normally, he would be unwilling to do the private tutoring job for less than HK$252 per hour. (Theo views the unpleasantness of the tutoring job as an offset against its salary.) Theo will decide to go to his friend's birthday party if and only if W is at most [Answer]. (In decimal numbers, with two decimal places, please.)