Jilin Dahui Training School has a class of 12 students, half of whom are boys and one third are girls.
Suppose there are x boys and y girls.
(x/2)+(y/3)= 12 ( 1)
(x/3)+(y/2)= 13 (2)
Solve equation X= 12
y= 18
x+y= 12+ 18=30
There are 30 students in this class.