Subject: Algebra/dimensions
Name: Ben
Who are you: Student

A rectangle's length is 8 cm. greater than its width. Its perimeter is 128 cm. Find its dimensions.


Hi Ben,

We have two solutions for you.

Did you draw a diagram?

In my diagram the length of the short side is x cm so the length of the long side is
x + 8 cm. Hence the perimeter is

x + 8 + x + x + 8 + x cm

But you know the perimeter is 128 cm. What is x?



Hi Ben.

The way I would solve this is to first give variable names to the two
things we want to find: the length L and the width W.

The perimeter is 128 so:
128 = L + W + L + W

And the length is 8 more than the width so:
L = W + 8

That last line means that wherever you see L, you can substitute "W + 8". So let's do that in the first equation:
128 = (W + 8) + W + (W + 8) + W

Can you solve it now?
Stephen La Rocque>