The students donated books for the "Hope Project". The fourth grade donated 750 books, 136 more than the third grade, and the second grade was 64 fewer than the third grade. How many books are donated for the second grade?
同学们为"希望工程"捐书，四年级捐书750本，比三年纸多捐136本，二年级比三年级少64本．二年级捐书多少本？
<gadget id="calculator">750 - 136 - 64</gadget>
<output>550</output>

<result>550</result>