posted by Mazhar .
In a class, 2/7 of the pupils are girls. 1/2 of the girls and 1/3 of the boys in the class wear glasses. If 10 boys wear glasses, how many of the girls wear glasses?
total number of students ---- x
number of girls = (2/7)x
number of boys = (5/7)x
number of girls with glasses = (1/2)(2/7)x = (1/7)x
number of boys with glasses = (1/3)(5/7)x = (5/21)x
given: (5/21)x = 10
solve for x, and sub into my definition