Subtract the product of 0.4 and 5.5 from 10.6, divide the difference by 2.1, what is the quotient?
10.6减去0.4与5.5的积，所得的差除以2.1，商是多少？
<gadget id="calculator">0.4 * 5.5</gadget>
<output>2.2</output>

<gadget id="calculator">10.6 - 2.2</gadget>
<output>8.4</output>

<gadget id="calculator">8.4 / 2.1</gadget>
<output>4</output>

<result>4</result>