320 square foot room. width is 4/5 length. what is width and length?

I think the answers might be,
length=20 
width=16

to find the answer you have to build an equation,
x=the length of the room
equation,  320=4/5×x+x

when you solve this equation, you'll get 200=x 
so if the length is 200 the width should be 160,beacuase if you divide 320 by 5 and multiply by 4 you'll get 160..
but when you multiply them both to get the area you'll get 32000, so it doesn't answer your question correctly.
but if you look carefully you could see there are three 0s in the 32000 and three zeros in 200 and 160 combined, so to match your question we have to take away two 0s from the 32000,and if we do that we have to take one 0 from 200 and 160 each too. so then it will be,
16×20=320, which matches your question... 

i don't know the accurate theory behind this but i hope this will help you