Xiaohong reads a 124-page book of fairy tales. After 5 days of reading, there are still 77 pages left. How many pages has she read? (solution by equation)
小红看一本124页的童话书，看了5天后还剩77页没有看．她已经看了多少页？(用方程解)
<gadget id="calculator">124 - 77</gadget>
<output>47</output>

<result>47</result>