To work out the profit, firstly, you have to work out the cost of buying them, which is $15 multiplied by 100, which is $1500. You then have to work out what he sold them all at, which is $29.99 multiplied by 100, which is $2999. You then have to subtract $1500 from $2999, giving you $1499. Therefore, Ace made $1499 in profit.
Hope this helps :)
