Yangyang reads a storybook, and has already read (2/5), and there are 75 pages left to read. How many pages does this storybook have? (This problem is solved by equation)
洋洋看一本故事书，已经看了(2/5)，还剩75页没有看，这本故事书一共有多少页？(此题用方程解)
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">75 / (3/5)</gadget>
<output>125</output>

<result>125</result>