Factorise:                  

(a)

128-

x

x

x

x

x

x

160-

x

x

x

x

x

320-

x

x

x

x

x

x

(b)

36-

x

x

x

54-

x

x

x

75-

x

x

(c)

12-

x

x

26-

x

78-

x

x

42-

x

x