Question

Find the answer to the table shown below.

Answer 1

height x length=0.8
1.0 times blank=0.8
divide both sides by 1.0
blank=0.8/1=0.8

length=0.8

Answer 2

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