A store bought a batch of pens, bought each pen for 11.9 yuan, and sold each pen for 14 yuan. There are still 150 pens in the store, but the profit has been 420 yuan. How many did you buy?
某商店购进一批笔，购进每支11.9元，卖出每支14元，现商店还有150支，但已获利润420元．购进了几支？
<result>150</result>