Normally if you have the things legnth
and height, you and another thing, then normally the other thing
would be area and you would have 2 given and 1 to solve.
Probably your question is
legnth=?
Height=1.0
decimal part is confusing, I am
guessing that you mean area
area=0.8
so use formula
height times legnth=0.8 1.0 times blank=0.8 divide both sides by 1.0 blank=0.8/1=0.8 blank=0.8 legnth=0.8