The elder brother came home from school and walked at a speed of 6 kilometers per hour. Eighteen minutes later, the younger brother also came home from the same school. The younger brother rides a bicycle to catch up with the elder brother at a speed of 15 kilometers per hour. After a few minutes, can the younger brother catch up with the older brother? Use two methods of solving equations and calculating formulas.
哥哥放学回家，以每小时6千米的速度步行，18分钟后，弟弟也从同一所学校放学回家．弟弟骑自行车以每小时15千米的速度追哥哥，经过几分钟弟弟可以追上哥哥？使用解方程和算式两种方法．
<gadget id="calculator">18 / 60</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">15 - 6</gadget>
<output>9</output>

<gadget id="calculator">(3/10) / 9</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">6 * (1/30) * 60</gadget>
<output>12</output>

<result>12</result>