document.write( "Question 1007091: in a class of 30 students, 18 students study history, 16 study geography and 3 study neither subject. how many students undertake geography but not history \n" ); document.write( "

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\n" ); document.write( "In a class of 30 students, 18 students study history, 16 study geography and 3 study neither subject. How many students undertake geography but not history?
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document.write( "How many students of the class study at least one of the two subjects, history or geography? 30 - 3 = 27 students.\r\n" );
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document.write( "Now add 18 who study history and 16 who study geography. You will get 18 + 16 = 34.\r\n" );
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document.write( "Why it is more than 27? - It is because some of 18 + 16 study both history and geography.\r\n" );
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document.write( "How many students study both subjects?  The answer is: (18 + 16) - 27 = 34 - 27 = 7. \r\n" );
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document.write( "Now we know that 16 students study geography; of them 7 study history.\r\n" );
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document.write( "Thus, it is easy to determine the number of those who study geography only.\r\n" );
document.write( "It is 16 - 7 = 9.\r\n" );
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document.write( "Answer. The number of students who study only geography is 9.\r\n" );
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