Question 1132863
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<pre>
Let x be the number of students in the class.  


There are two ways to calculate the number of those who study at least one subject, Geography  <U>OR</U>  Statistics.


From one side, this number is  N = (x-4).


From the other side, this number is

    N = 0.5x + 0.6x - 8.


Indeed, 0.5x represents the half of student in the class, who take Geography.

        0.6x represents three-fifth of the students in the class, who take Statistics.

        And I subtracted 8 from the sum, who take both classes and whom I calculated twice, when added 0.5x and 0.6x.


It gives me an equation


    x - 4 = 0.5x + 0.5x - 8


to find x.


So, I simplify the equation


    8 - 4 = 0.5x + 0.6x - x

    4 = 0.1x  


and obtain the

<U>ANSWER</U>.  There are  x= {{{4/0.1}}} = 40 students in the class.
</pre>

Solved, explained, answered and completed.