Wang Fang read a 290-page book and planned to finish it in 7 days. Actually, I read 20 pages a day in the first 4 days. If I want to read it as planned, how many pages should I read every day?
王芳看一本290页的书，计划7天看完．实际前4天每天看了20页，要按计划看完，以后每天应看多少页？
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<gadget id="calculator">290 - 80</gadget>
<output>210</output>

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

<gadget id="calculator">210 / 3</gadget>
<output>70</output>

<result>70</result>