Ms. Brady has 28 students in her class. The ratio of boys to girls in the class is 2 to 5. How many new boys must be added to the class to make the ratio of boys to girls 1 to 2?

28 students ... ratio of boys to girls is 2 to 5 ... added = 7

2/7 (28) = 56/7 = 8 boys

5/7 (28) = 140/7 = 20 girls

so right now, there is 8 boys and 20 girls (8/20 = 2/5)

so lets add 2 boys ... making it 30 students

10 boys and 20 girls = 10/20 = 1/2 or 1 to 2

answer is : u have to add 2 boys to get a ratio of boys to girls = to 1:2