Question

in a class number 49 students,number of girls 2/5 of the boys . find the number of boys in the class

Answer 1

Y(No. of girls) = 2/5X (No. of Boys

X+Y=49
X+2/5X= 49
7/5X= 49
x=35

Y=14 [No. of girls]

Answer 2

total number of students = 49
number of boys = x
number of girls = 2/5 of x

total number of students = x + 2/5 * x = 49 ( * is multiplication sign)
                                        = 5x/5 + 2x/5 = 49
                                        = 7x/5 = 49
                                        = 7x = 49 * 5
                                        = x = 49 * 5 / 7 (7 will cut 49 as 7x7=49)
                                        = x = 7*5
                                        = x = 35.


number of boys = x = 35
number of girls = 2/5 * x = 2/5* 35 (5 will cut 35 as 5x7=35)
                                        = 2*7= 14
total number of girls = 14