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math length of rectangle

a rectangle has an area of 12 m2 and a width of 400 cm . what is the length of the rectangle ?

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Sol L. | NYU Grad for Reading TutoringNYU Grad for Reading Tutoring
5.0 5.0 (15 lesson ratings) (15)
This problem involves two different types of measurements: meters and centimeters.
We want all the measurements in a problem to be same.
So let's first convert 400 cm to meters.
We know 100 cm = 1 meter (this should be memorized) so 400 cm must be 4 meters 
This is an algebra problem so in any algebra problem you always want to write out the algebraic equation.

The algebraic equation for area of a rectangle is length times width or
A = L x W.

The problem gives us the area: A= 12 meters squared
And the width: W= 4 meters
Let's rearrange the equation to find and isolate length: L = A / W  

Now we just plug in: L = 12 meters / 4 meters

12 divided by 4 = ?
Arturo O. | Experienced Physics Teacher for Physics TutoringExperienced Physics Teacher for Physics ...
5.0 5.0 (66 lesson ratings) (66)
A = 12 m2
W = 400 cm = 4m
A = LW ⇒ L = A/W = (12 m2) / (4m) = 3m
The length is 3m.


If needed you can convert the 3m back to centimeters.
Each meter is 100 cm so 3m = 300 cm for the length.