When Li Ming reads a book, he has already read 6 pages less than (2/3) of the whole book, and there are still (2/5) of the whole book that he has not read. How many pages are there in the whole book?
李明看一本书，已经看的比全书的(2/3)少6页，还剩全书的(2/5)没看，全书多少页？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(2/5) - (1/3)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">6 / (1/15)</gadget>
<output>90</output>

<result>90</result>