A road of 800 meters is built, and x meters are repaired every day. After 3 days of repairing, how many meters are left to be repaired.
修一条800米的公路，每天修x米，修了3天，还剩多少米没修．
<gadget id="calculator">800 - 3</gadget>
<output>797</output>

<result>797</result>