Xiao Ming reads a story book. I read the whole book (1/6) on the first day, and read less (1/7) of the whole book on the second day than on the first day. How much of the whole book did you read in two days?
小明看一本故事书．第一天看了全书的(1/6)，第二天比第一天少看了全书的(1/7)．两天一共看了全书的几分之几？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

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

<gadget id="calculator">(1/6) - (1/7)</gadget>
<output>1/42 = around 0.02381</output>

<gadget id="calculator">(1/42) + (1/6)</gadget>
<output>4/21 = around 0.190476</output>

<result>4/21 = around 0.190476</result>