Honestly, I have no idea what it means by decomposition, but this is my best bet on what it means: Dividing the polygon into smaller, easier sections and solve for area and add them up.
I hope this helps you
x^2-6x+9= -1
(x-3)^2= -1
(x-3)^2=i^2
x-3=i
x=3+i
x=3-i
or we can find disctirminant
x^2-6x+10=0
a=1
b= -6
c=10
disctirminant=b^2-4ac
disctirminant=(-6)^2-4.1.10
disctirminant=36-40
disctirminant= -4
i^2= -1
x1,2= -b (+,-) square root of disctirminant /2a
x1= -(-6)+square root of -4/2.1
x1=6+2i/2=3+i
x2= -(-6)-square root of -4/2.1
x2=6-2i/2=3-i
It would be 1/7 since you essentially are dividing by 7 to cancel out the original scaling.