The width of a rectangular poster is half its length. the area of the poster is 128 square feet. what is the width of the poster?

Area= width * length
w=1/2 length
Area+ 128 sqr ft

Plug in the information you know into the Area formula.

128 ft2= w * l
128 ft2= (1/2 l)(l)
128 ft2=l/2
multiply both sides by 2 to get rid of the fraction
256 ft2 = l
take the square root of 256
16=length in feet

1/2length = width = 8 feet

Hope this helps!  :)