Ding Ding reads a 200-page book. He reads 1/4 of the whole book on the first day, and 45 pages on the second day. How many pages are left?
丁丁看一本200页的书，第一天看了全书的(1/4)，第二天看了45页，还剩多少页没有看．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">200 * (1/4)</gadget>
<output>50</output>

<gadget id="calculator">200 - 50 - 45</gadget>
<output>105</output>

<result>105</result>