The longest underwater tunnel runs under the English Channel from Folkestone (England) to Calais (France). The route consists of two railway tunnels that are [[$ 49.94 $]] km long and [[$ 7.6 $]] meters in diameter. The tunnels were built between 1987 and 1990 and cost around € [[$ 15]] billion. Calculate the total volume of the two tunnels.

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Answer: The total volume of the tunnels is m[[$ ^3 $]].