Question

there are 42 student in a class. out of these , 3/4 of boys and 2/3 of girls come to school by bus . the total number of students in the same class who come by bus is 30. how many boys are there in the class ?

Answer 1

Answer:

12 is the answer

Step-by-step explanation:

Answer 2

Answer:

X Boys in the class.

Y Girls in the class.  

3x/4 + 2y/3 = 30,

Multiply by 12:

Eq1: 9x + 8y = 360.

x/4 + y/3 = 42-30 = 12,

Multiply by 12:

Eq2: 3x + 4y = 144.

Multiply Eq2 by -3 and add:

9x + 8y = 360

-9x - 12y = -432

Sum: -4y = -72, Y = 18.

3x + 4*18 = 144, X = 24.

Step-by-step explanation:

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