When a=7.6, b=5, c=0.4, what is the value of (ab-b)c?
当a=7.6，b=5，c=0.4时，求(ab-b)c的值是多少．
<gadget id="calculator">7.6 * 5</gadget>
<output>38</output>

<gadget id="calculator">38 - 5</gadget>
<output>33</output>

<gadget id="calculator">33 * 0.4</gadget>
<output>13.2</output>

<result>13.2</result>