Question

The 3rd grade classroom has a perimeter of 130 feet. if it is 25 feet wide, how many feet long is the classroom

Answer 1

Let W be the wide and L the length of the classroom, then we can write

$2\times W+2\times L=130$

Since W=25 feets, we get

$\begin{gathered} 2\times25+2\times L=130 \\ 50+2\times L=130 \end{gathered}$

If we move 50 to the right hand side as -50, we obtain

$2\times L=130-50$

since 130-50=80, we get

$2\times L=80$

Now, if we move the coefficient 2 to the right hand side, we obtain

$\begin{gathered} L=\frac{80}{2} \\ L=40 \end{gathered}$

that is, the lenght of the classroom is equal to 40 feets.