Hey!
You can make a proportion:

Cross multiply

Divide by 2

<em>5 pounds would cost $10.50</em>
Good luck and hope this helps! :)
Answer:
Length = 90 inch.
width = 30 inch
Let width of the rectangle = x inch.
So the length = 3x inch.
Perimeter = 2(length + width) = 2 (3x + x) = 8x.
So,
length = 3x = 3(30) = 90 inch.
width = x = 30 inch
Assuming the size of the whole remains constant, as you divide the whole into more pieces, each piece must be smaller. For example, when a whole is divided into four pieces vs nine pieces, 1/4 of the whole is larger than 1/9 of a whole.