Answer:
they'll need 200 more cans
Areashaded=areabigcircle-areasmallcircle
areacircle=pir^2
d/2=r
big diameter=20.4, so radius i 20.4/2=10.2cm
small is 10.8/2=5.4
so
big-small
pi10.2^2-pi5.4^2
pi(104.04-29.16)
pi(74.88)
using 3.14=pi
235.1232 cm^2
answer is B