Word problem with a ratio

Question

Your 3rd grade classroom has 32 boys and girls. two-thirds of the boys and three-fourths of the girls are going on a field trip. There are 9 children left. What is the ratio of boys and girls in your class?

Answer 1

b + g = 32

2b/3 + 3g/4 + 9 = 32

12(2b/3 + 3g/4) = 12(23)

8b + 9g = 276

 

b = 32 - g

 

8(32 - g) + 9g = 276

256 - 8g + 9g = 276

g = 20

 

32 - 20 = 12

 

12:20 = 3:5