Wang Jun leaves home at 7:25 in the morning and arrives at school at 7:40. How much does it cost to go back and forth to school twice?
王军早上7：25从家出发，7：40到校，往返学校两趟要多少分．
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>