Kiera's estimate is less than the actual area
Step-by-step explanation
Step 1
the area of a rectangle is given by

then, let
length=28.5 ft
width=11.4 ft
replace,

Step 2
now, with Kiera's estimation
let
length=28
widht=11
replace to find the area

so, Kiera's estimate is less than the actual area.
i hope this helps you