Answer:
66,666666666666666666666666666666666667% :))
Step-by-step explanation:
total number of students in 1 class: 12 + 6 = 18 students
percentage of student wearing glasses are:

Done :))
Step 1
Find the area of one equilateral triangle
Applying the law of sines

in this problem
a=b=7 cm
C=60 degrees
so

cm²
Step 2
To calculate the area of the hexagon multiply the area of one equilateral triangle by 
cm²
therefore
the answer is the option
73.5 sqrt 3cm²