An observer detects two explosions that occur at the same time, one near her and the other 100 km

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concept of modern physic 6 edition beiser chapter 1 problem 52 solution.An observer detects two explosions that occur at the same time,
one near her and the other 100 km away. Another observer
finds that the two explosions occur 160 km apart. What time
interval separates the explosions to the second observer?

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