Question 27948
If you draw a rectangle and label the length (L) and width (W), you will see that the perimeter is the sum of all the sides, i.e. 
{{{P = L + W + L + W}}}
{{{P = 2L + 2W}}}

Now, let's set W = x.  Then, since the length is 2cm longer than the width, we can say L = x+2.  
We also know that the perimeter is 56cm.  
So, plugging these new equations into our original equation, we have:

{{{P = 2L + 2W}}}
{{{56 = 2(x+2) + 2x}}}

Now, we can solve this equation for x.

{{{56 = 2x + 4 + 2x}}}   [distribute the 2 to the tokens within the parentheses]


{{{56 = 4x + 4}}}  [combine like terms]


{{{52 = 4x}}}  [subtract 4 on both sides]


{{{13 = x}}}  [divide both sides by 4 to isolate x]

So, to get the dimensions, we go back to the equations we wrote:
W = x. 
L = x+2. 

So, the width is 13cm, and the length is 15cm.