# Thread: Word problem using a three-step method

1. ## Word problem using a three-step method

The perimeter of a triangle is 240 mm. If the long side of the triangle is seven times the length of the smallest side and the other side is four times the length of the smallest side, find the length of all three side.

Smallest side = ? mm
Middle side = ? mm
Longest side = ? mm

I would appreciate some help please! thanks you!

2. Congratulate your teacher on proposing an impossible idea.

You cannot have a triangle with the given ratios.

But since your teacher will likely get defensive, just humor him or her and solve for the lengths using a basic equation, ignoring the laws of physics.

Let the smallest side be $\displaystyle l$

then

$\displaystyle l+4l+7l=240$

solve for $\displaystyle l$

once you do,

$\displaystyle l=$smallest side
$\displaystyle 4l=$medium side
$\displaystyle 7l=$longest side

Spoiler:

$\displaystyle 20=$smallest side
$\displaystyle 4*20=80=$medium side
$\displaystyle 7*20=140=$longest side