A group of 150 lamps is being marked down from $60 each to $…

A group of 150 lamps is being marked down from $60 each to $49.99. At the first markdown, 60 are sold. The remaining lamps are marked to $39.99 and 30 are sold. Finally, the remaining lamps are reduced to $19.99 and another 30 are sold. What is the total markdown $ amount?