the length of a rectangle is 5 centimeters less than it width. The perimeter of the rectangle is 80cm. What are the dimensions of the rectangles what is the answer?

Question

michele_laino · Answer

If I call with $w$ and with$l$ the width and the length respectively, of such rectangle, then we can write the subsequent algebraic system:
$$\left\{ \begin{gathered}
  l = w - 5 \hfill \
  2\left( {l + w} \right) = 80 \hfill \ 
\end{gathered}  \right.$$

michele_laino · Answer

please, solve that system, using the substitution method

anonymous · Answer

i dont understand it @Michele_Laino

welshfella · Answer

One thing - the length , by definition,  is longer than the width.

michele_laino · Answer

for example, I substitute the first equation into the second one, so I get this:
$$\begin{gathered}
  2\left( {w - 5 + w} \right) = 80 \hfill \
   \hfill \
  w - 5 + w = 40 \hfill \
   \hfill \
  2w - 5 = 40 \hfill \ 
\end{gathered} $$
what is $w$?