Question 1150617
Number of girls = x
Number of boys = x - 18
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{{{(x - 18)/(x + (x - 18))}}} = 0.4
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{{{(x - 18)/(2x - 18))}}} = 0.4
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Cross-multiply:
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x - 18 = 0.4(2x - 18)
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x - 18 = 0.8x - 7.2
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0.2x = 10.8
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x = 54
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Number of girls = x = 54
Number of boys = x - 18 = 54 - 18 = 36
<pr>
There are 54 girls in the class and 36 boys in the class.  Therefore, there are 90 students in the class altogether.