Xiaohua reads one book a week, 40 pages a day in the first 3 days, and the whole book (1/7) in the next 4 days. How many pages does Xiaohua read in a day on average?
小华一星期看完一本书，前3天每天看40面，后4天每天看全书的(1/7)，小华看这本书平均每天看几页？
<gadget id="calculator">3 * 40</gadget>
<output>120</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/7) * 4</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">120 / (3/7) / 7</gadget>
<output>40</output>

<result>40</result>