数学题：一条公路，甲队修完要10天，乙队修完要8天。两队合修4天后，还剩下5000米，这条路共长多少米？

数学题解答：把这条公路看作“1”。

甲队每天修：1/10

乙队每天修：1/8

两队4天共修：(1/10 + 1/8) × 4 ＝9/10

还剩：1 – 9/10 = 1/10

剩下的5000米就是这条公路的1/10，所以这条公路长：

5000 ÷ 1/10 = 50000（米）

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