In a class, there are 27 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 ? Choose the correct choice from the following options.
A) 6 B) 12 C) 18 D) 24 E) 26
Explanation:   Let the number of boys be x. Then, (3/4)x = 27 or x = 27 x(4/3) = 36.   If total number of students is y, then (2/3) y = 36 or y = 36 x (3/2) = 54.   Therefore Number of girls in the class = (54 - 36)= 
<gadget id="calculator">(54 - 36)</gadget>
<output>18</output>
18.   Answer: 18
<result>C</result>
In a class, there are 27 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 ?