80 minus 5 times a number. The difference is 15, what is this number?
80减去一个数的5倍．差是15，这个数是几？
<gadget id="calculator">80 - 15</gadget>
<output>65</output>

<gadget id="calculator">65 / 5</gadget>
<output>13</output>

<result>13</result>