On the "Six, One" Children's Day, the school plans to buy 60 pens priced at 8 yuan to reward "three good students". The preferential conditions of the two stores are as follows: store A sells at 15% off; store B returns 15 yuan in cash when it spends 100 yuan. Please do the math, which store to buy pens for school is cheaper? How much is it cheaper?
"六、一"儿童节学校准备买60支定价8元的钢笔奖励给"三好学生"，恰好有两个文化用品店开展"六、一"促销活动．两个店的优惠情况如下：甲店按八五折出售；乙店满100元返还15元现金．请你算一算，学校去哪家店买钢笔比较便宜？便宜多少元？
<gadget id="calculator">60 * 8</gadget>
<output>480</output>

<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<gadget id="calculator">60 * 8 * 0.85</gadget>
<output>408</output>

<gadget id="calculator">480 - 60 - 408</gadget>
<output>12</output>

<result>12</result>