Xiaochun reads a novel. If he reads 35 pages a day, he will finish the book one day later than the prescribed time; if he reads 40 pages a day, he must read 5 pages less on the last day. If he reads 39 pages a day, how many pages should he read in the last day? Did you finish reading it on time?
小春读一本小说，若每天读35页，则读完全书比规定时间迟一天；若每天读40页，则最后一天要少读5页，如果他每天读39页，最后一天应读多少页才按规定时间读完？
<gadget id="calculator">35 + 5</gadget>
<output>40</output>

<gadget id="calculator">40 - 35</gadget>
<output>5</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">40 * 8</gadget>
<output>320</output>

<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">7 * 39</gadget>
<output>273</output>

<gadget id="calculator">320 - 5 - 273</gadget>
<output>42</output>

<result>42</result>