I need math help! My boyfriend usually helps me figure things out, but he is not here right now, and this is going to drive me crazy!

A December promotion of 1500 vases to retail at $40 each is planned. The buyer requires a 48.5% markup and has made an initial purchase consisting of 1200 units costing $23 each. What is the cost to be paid on each remaining unit? Is the buyer in a predicament?...Okay, the answer is $11, however I don’t know how or why. Any help would be much appreciated!!!