The toy store bought 150 toy pistols at a price of 8 yuan each, and later sold them at a retail price of 12 yuan each. How many percent has the retail price of this batch of toy pistols increased compared to the purchase price?
玩具店以每支8元的价格购进了150支玩具手枪，后来以每支12元的零售价出售．这批玩具手枪的零售价比进价提高了百分之几？
<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<gadget id="calculator">4 / 8</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>