Question

26 students, each girl drew a triangle and each boy drew a rectangle. If there were 92 sides drawen by the students, how many girls were in the class?

Answer 1

Let x = number of girls
26-x = number of boys
3x = number of lines the girls drew
4(26-x)= number of lines the boys drew.
Now the sum is equal to 92

Do you need any more guidance, or can you take it from there?

Answer 2

Don't look at this until you have at least tried to solve it.
3x+4(26-x)=92
3x+104-4x=92
3x-4x=92-104
-x=-12
x=12 (12 girls)
26-12= 14 (14 boys)