天風出版社數學小六升中一有D數唔識做!請教!快D!

a
56=2x2x2x7
64=2x2x2x2x2x2
HCF:8
LCM:448
b
48=2x2x2x2x3
72=2x2x2x3x3
120=2x2x2x3x5
HCF:24
LCM:720

1.
2 |24 42 60
|_________
2 |12 24 30
|_________
3 | 6 12 15
|_________
2 4 5

HCF:2x2x3=12
LCM:2x2x3x2x4x5=480

2.
5 |15 60 75
|_________
3 | 3 12 15
|_________
1 4 5

HCF:5x3=15
LCM:5x3x1x4x5=300


方程:
若某矩形的面積為40平方厘米,而它的長及闊分別為8厘米及W厘米,求W的值
40/8=5

以上都是easy question FOR P.4-5 pupils