We need more info on this.
A. 80 students
B. 12 students
Well 3 feet=1 yard
so the conversion factor is 3ft/1yd
so 12 yards converted to feet is
12yd times 3ft/1yd
the yd will cancel and you will be left with 36 feet
each banner is 1 foot so 36/1=36
she can make 36 banners