The students in three classes are in the ratio 2:3:5. If 20 students are increased in each class, the ratio changes to 4:5:7. The total number of students before the increase were :
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Let the no. of student be 2x, 3x and 5x
(2x+20): (3x+20): (5x+20) =4:5:7
(2x+20)/4 = (3x+20)/5 = (5x+20)/7
5(2x+20) = 4(3x+20)
10x+100 = 12x+80
-2x = -20
x = 10
Hence the total no of students before increase
=2x+3x+5x
=10x
=10×10
=100
(2x+20): (3x+20): (5x+20) =4:5:7
(2x+20)/4 = (3x+20)/5 = (5x+20)/7
5(2x+20) = 4(3x+20)
10x+100 = 12x+80
-2x = -20
x = 10
Hence the total no of students before increase
=2x+3x+5x
=10x
=10×10
=100
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