Twice a number is 2.4 less than the product of 12.8 and 0.5. Find this number.
一个数的2倍比12.8与0.5的积少2.4，求这个数．
<gadget id="calculator">12.8 * 0.5</gadget>
<output>6.4</output>

<gadget id="calculator">6.4 - 2.4</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<result>2</result>