The school is between Yingying's house and Nini's house. There are 4 roads from Yingying's house to school. There are 5 roads from school to Nini's house, and how many roads are there from Yingying's house to Nini's house.
学校在莹莹家和妮妮家中间．从莹莹家去学校有4条路．从学校去妮妮家有5条路，从莹莹家去妮妮家有多少条路．
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<result>20</result>