The teacher bought 48 diaries, which were less than the math books (1/7). How many math books did the teacher buy?
老师买了48个日记本，买的日记本比数学本少(1/7)，老师买了多少个数学本？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 - (1/7)</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">48 / (6/7)</gadget>
<output>56</output>

<result>56</result>