I'm in grade 5 and I need help on an area and perimeter question. The area of a rectangle is 300mm and the length of it is 15 mm. I need to find out the width of this rectangle.

What don't you understand about my previous answer to your question?

http://www.jiskha.com/display.cgi?id=1423613141

To find the width of the rectangle, you'll need to use the formula for the area of a rectangle:

Area = length × width

You are given the area of the rectangle, which is 300mm, and the length, which is 15mm.

To find the width, you can rearrange the formula as follows:

Width = Area / Length

Now you can plug in the given values:

Width = 300mm / 15mm

To divide 300mm by 15mm, you simply divide the number 300 by the number 15.

300 ÷ 15 = 20

So, the width of the rectangle is 20 mm.