When a batch of new books of "Happy Bookstore" are sold at 70% of the price, they can still get 40% of the profit. So, what is the expected profit margin when pricing?
"快乐书屋"的一批新书按定价的70%出售时，仍能获得40%的利润，那么，定价时所期望的利润率是多少？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(7/5) / (7/10)</gadget>
<output>2</output>

<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<result>1</result>