Hope elementary school students saved 40.2 yuan by repairing tables and chairs, and saved 3.7 yuan less by binding books than repairing tables and chairs. How much did you save by binding the books?
希望小学的同学修理桌椅节约了40.2元，装订图书比修理桌椅少节约了3.7元．装订图书节约了多少元？
<gadget id="calculator">40.2 - 3.7</gadget>
<output>36.5</output>

<result>36.5</result>