The school bought 195 new books, including 120 story books and the rest are nature books. How many more storybooks than nature books?
学校买来195本新书，其中有故事书120本，剩下的是自然书．故事书比自然书多多少本？
<gadget id="calculator">195 - 120</gadget>
<output>75</output>

<gadget id="calculator">120 - 75</gadget>
<output>45</output>

<result>45</result>