Boris' mountain has an elevation 2,500 feet shorter than Hugo's mountain, or 10,000-2,500=<<10000-2500=7500>>7500 feet above sea level.
If Hugo climbed his mountain 3 times, his total climbing distance would be 3*10,000=<<3*10000=30000>>30,000 feet.
To climb a total of 30,000 feet, Boris would need to need to climb his mountain 30,000/7,500=<<30000/7500=4>>4 times.
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