If a piece of cloth is made for an adult, it can be made into 12 sets of clothes. If it is made for a child, it can be made into 20 sets of clothes. It is known that an adult uses 0.8 meters more cloth than a child. How many meters does this piece of cloth have?
一块布给成人做，可做12套服装，如给儿童做，可做20套服装，已知成人每套比儿童多用布0.8米，这块布共有多少米．
<gadget id="calculator">12 * 0.8</gadget>
<output>9.6</output>

<gadget id="calculator">20 - 12</gadget>
<output>8</output>

<gadget id="calculator">9.6 / 8</gadget>
<output>1.2</output>

<gadget id="calculator">1.2 * 20</gadget>
<output>24</output>

<result>24</result>