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The half-life of a certain radioactive element is 200 years. how will it take for a 100 pound chunk of this element to decay to a chunk that is 50 pounds?

In 1912, the original candidates for united states president were woodrow wilson and william h. taft. because of party disagreements, former president theodore roosevelt also decided to run and ended up splitting the vote with his fellow republican and incumbent, taft. in a certain state, the ratio of the popular vote of taft to roosevelt to wilson was approximately 35: 41: 63. if approximately 208,500 votes were cast in that state for the three candidates altogether, how many were cast for taft? a) 15,000 b) 45,000 c) 52,500 d) 69,500

The ratio of money in obi's wallet to rudy's wallet one day was 5: 2. obi spent ? 20 that day. obi now had ? 8 less than rudy. how much did they have initially altogether?