The students in three classes are in the ratio 4:6:9. if 12 students are increased in each class, the ratio changes to 7:9:12. then the total number of students in the three classes before the increase is ?
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Let the students in those three classes be 4x, 6x, 9x.
When 12 students are increased:-
4x+12 = 7x
6x+12=9x
9x+12=12x
let's take any one equation....
4x+12=7x
4x-7x= -12
-3x = -12
x= -12/ -3
x= 4
students in three classes before the increment:
4x = 4*4=16
6x= 6*4=24
9x= 9*4=36
When 12 students are increased:-
4x+12 = 7x
6x+12=9x
9x+12=12x
let's take any one equation....
4x+12=7x
4x-7x= -12
-3x = -12
x= -12/ -3
x= 4
students in three classes before the increment:
4x = 4*4=16
6x= 6*4=24
9x= 9*4=36
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