The construction team is going to dig a canal, and they have already dug 35.4 meters. The undug is 6.8 meters longer than the dug. How long is this canal in meters?
施工队要挖一条水渠，已经挖了35.4米，没挖的比已挖的多6.8米，这条水渠全长多少米？
<gadget id="calculator">35.4 + 6.8 + 35.4</gadget>
<output>77.6</output>

<result>77.6</result>