Answer :
lets say x,y,z are the unknown variables,
11+x=y*16=z/2=209
so first solve for z
z/2=209
z=418
y*16=z/2
y=418/32
y=209/16
x+11=y*16
x=209/16*16-11
x=209-11
x=198
missing area is
11+198=209/16=418/2=209
11+x=y*16=z/2=209
so first solve for z
z/2=209
z=418
y*16=z/2
y=418/32
y=209/16
x+11=y*16
x=209/16*16-11
x=209-11
x=198
missing area is
11+198=209/16=418/2=209