40%=4/10=4*(1/10)
60%=6/10=6*(1/10)
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1/10 of 300 is 30, therefore 4/10 of 300 is 120.
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1/10 of 300 is 30, therefore 6/10 of 300 is 180.
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So, 120 students voted for Jennifer and 180 students voted for Kevin therefore, Kevin received 60 more votes.