The length of a rectangle is twice that of the width. the perimeter of the rectangle is 24 cm. what is the width of the rectangle? the width of the rectangle is. simple working out is appreciated.

We can solve this question by using simultaneous equations (2 equations for 2 unknowns).

Let the width be w and the length by l. Write 2 equations from the given info. 
l = 2w   (length of the rectangle is twice that of width) (1)
(l + w) x2 = 24   (perimeter is 24) (2)

Substitute (1) into (2), 
(2w + w) x 2 = 24
2w + w = 24/2
3w = 12
w = 4

Therefore, the width of the rectangle is 4cm.