For me being 100% honest:
grade 9-11 no homework, pay attention in class and study night before.
Grade 12: pay attention more in class, do some homework when concepts hard, study night before.
Uni: Read notes, do class homework, read textbook, study week before.
Let L be the length
Let w be the width
Let p be the perimeter
L+w+L+w=p
L=w+20
3L+2w+3L+2w=240
Sub the first equation in for L in the second equation and solve for w
3(w+20)+2w+3(w+20)+2w=240
3w+60+2w+3w+60+2w=240
10w+120=240
10w=240-120
10w=120
W=120/10
W=12
Sub w into the first equation and solve for L
L=w+20
L=12+20
L=32
Hope this helps!
