Xiaoqing ordered draft books by herself, each with 70 pages. After ordering 5 books, there are 50 sheets left. How many sheets did she have?
小青自己订草稿本，每本70页．订了5本后还剩50张纸，她原来有多少张纸？
<gadget id="calculator">70 * 5</gadget>
<output>350</output>

<gadget id="calculator">350 + 50</gadget>
<output>400</output>

<result>400</result>