The ratio of boys to girls is 7:5. The ratio of boys with glasses to boys without glasses is 1:6. The ratio of girls with glasses to girls without glasses is 1:3. What fraction of students wear glasses?

2/4

Step-by-step explanation:

sorry if im wrong though

  3/16

Step-by-step explanation:

Boys with glasses are 1/(1+6) = 1/7 of boys. Boys are 7/(7+5) = 7/12 of the group.

Girls with glasses are 1/(1+3) = 1/4 of girls. Girls are 5/(7+5) = 5/12 of the group.

The fraction of the group that wears glasses is ...

  (1/7)(7/12) +(1/4)(5/12) = 1/12 +5/48 = 9/48 = 3/16

3/16 of the students wear glasses.

Additional comment

It appears we can choose a multiple of 48 students to work out the detailed numbers. For 48 students, the ratio of boys to girls is 28 : 20. The ratio of boys with glasses to those without is 4 : 24, and the similar ratio for girls is 5 : 15. In our group of 48 students, 4 boys and 5 girls = 9 students wear glasses. The fraction is 9/48 = 3/16 as shown above.

answer: i don't understand it

step-by-step explanation: sorry