In a class, there are 18 boys who are over 160 cm tall. If these constitute three-fourths of the boys and the total number of boys is two-thirds of the total number of students in the class, what is the number of girls in the class?

Let the number of boys in the class = b

Given three-fourths of the boys in the class = 18

$$\Rightarrow$$  $$\frac{3}{4}$$b = 18

$$\Rightarrow$$  b = 24

Number of boys in the class = 24

Let the total number of students in the class = t

Given number of boys is two-thirds of the total number of students in the class

$$\Rightarrow$$  $$\frac{2}{3}$$t = 24

$$\Rightarrow$$  t = 36

Total number of students in class = 36

$$\therefore\ $$Number of girls in the class = 36 - 24 = 12

Hence, the correct answer is Option B